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Spadefoot of the Western Plains
- Colour
- Yellowish olive. Muzzle darker through midline. Indistinct curved dark band on the head between the eyes. Two curving (more or less parallel) dark bands, extending backward from the eyes. These bands are made up of closely placed spots, each spot containing a smooth orange-coloured tubercle at its centre. Similar spots with orange-red tubercles are scattered irregularly over the sides and posterior portion of the back. There may be four distinct light yellow bands running lengthwise along the back. There may be a dark spot on the canthus rostralis. Iris golden. Tibia spotted irregularly or vermiculated with dark. Underparts dingy white, purplish posteriorly; throat blackish.
- Measurements
- Size small, i.e. length 2 inches. Space between eyes equal to or greater than width of eyelid. Leg short; length of leg to heel equal to length of body forward to shoulder or ear. Tibia not longer than femur.
- Structure
- Skin smooth and fine in texture, with a few tubercles on the sides, posterior portion of the back, and on the tibias. Muzzle short in front of eyes (no longer than horizontal diameter of eye). Outline of jaw as seen from below, acuminate oval. Truncated muzzle elevated. Eyes face forward and outward; pupil vertical. Nostrils slightly farther apart than distance between eyes. No canthus rostralis. Ear indistinct. Top of head between the eyes anteriorly is horny-looking, also in front of this between the nostrils and on the end of the muzzle. It is not only horny-looking, but it is elevated in two arches from the front backward. (See Figs. 26 to 30.) Parotoids obscure or lacking. Hands unusually small and fingers short. Whole palm horny, so that the palm tubercles are not easily made out. Foot extensively webbed, but the webs are deeply indented. Inner sole tubercle not only large, but greatly extended, so that it is most effective in digging.
- Range
- Scaphiopus hammondii bombifrons is typical of the northern part of the Western plains. It ranges from northern Texas to Montana. It is reported from Montana, Dakota, Idaho, and Colorado.
This Spadefoot is especially characteristic of the elevated plains of the Western part of the continent. It has the habits of the Eastern Spadefoot (Scaphiopus holbrookii), in that it burrows during the greater part of the year, only coming out during heavy and continued rains. In its range it is very abundant, and so when it does appear, every ditch and pool of water may show representatives. Being dependent on rain, its breeding season varies greatly from year to year. Cope observed specimens in Montana in which the metamorphosis was completed August 20th. He observed in Idaho the full-grown, fat larvae with the tails unabsorbed trying to feed upon animal food. They were in small burrows that they had made in the wet sand some distance from the lake margin. Some of them, in which the metamorphosis of the mouth had proceeded so far that there was a wide gape, had whole grasshoppers (Caloptenus spretus.) in their mouths or partially projecting from them. This observation also was in August.
This Spadefoot croaks vigorously when taken in the hand. The throat swells into a resonating pouch wider than long, and widest just back of the jaws, in a line with the front of the arm insertions. The creature is very active and alert in habit. It burrows into sandy soil dexterously and rapidly, using the feet and legs to good effect. The curved horny elevations on the head combined with the shortness and thickness of the muzzle, produce a most curious pug-dog expression. The horny arches are probably closely connected with the burrowing habit, the head being used to keep the burrow open in front. The amount and hardness of this horny growth of the epidermis of the head varies in different specimens: there may be a thin dark-coloured layer only, or the horn may be thick and as black and hard as is the inner sole tubercle. In some specimens this black horny substance is found not only on the head but also in a broad dorsal band.
FAMILY III. BUFONIDAE: THE TOADS (Refer to pp. 7,9 and 44.)