BATRACHIAANOURA. gl 



OBSERV.- There is perhaps no species of the bufonine group which 

 has been described under the same variety of specific names as the 

 present one. Besides the unusual variations observable upon individuals 

 of nearly the same size and age, differences occur between individuals 

 at different ages of growth. The most striking of these differences 

 consist in the variation in the shape of the parotid glands : rhomboi- 

 dal, sometimes nearly as wide as long, at other times more than twice 

 as long as broad, and tapering posteriorly into a somewhat acute angle. 

 They may further assume an elliptical shape, from twice or three times 

 as long as broad. These bodies, in the three desiccated specimens 

 brought home by the Expedition, exhibit a subelliptical shape, the 

 length of which is a little more than twice their width. Other dif- 

 ferences, comparatively superficial, are observed in the coloration, of 

 which we speak below, having a few more remarks to make with 

 regard to structure. 



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DESCR. To whatever extent the variations just alluded to may go, 

 it will always be easy to recognize the marine toad (B. marinus or 

 agua}, by the structure of the upper surface of its head, upon the 

 middle of which a broad depression, tapering forwards and widening 

 behind, may be seen. It is limited anteriorly and laterally by a con- 

 spicuous ridge, constituting an acute angle, extending from the tip of 

 the snout to the eyes. The ridge thence extends over the eyes, slightly 

 diverging from the medial line of the cranium, and passing behind the 

 orbit, to meet a subcrescentic and transversal ridge, situated above the 

 tympanum. In advance of the eye, and extending vertically over the 

 line of the canthus rostralis, a similar swollen ridge exists, being con- 

 nected above with the supra-orbital one. Thus, the eyes are surrounded 

 superiorly, anteriorly, and posteriorly with an elevated ridge. The 

 cephalic groove, posteriorly, is even with the surface of the body. 

 Occasionally, a swelling may be observed, extending from the poste- 

 rior curve of the lateral ridge obliquely towards the occiput, the sur- 

 face of which is striated or furrowed. The snout is almost perpendi- 

 cular in front; the nostrils are situated immediately beneath the ridge. 

 The eyes are large, almost circular. The tympanum, though conspi- 

 cuous, is comparatively of moderate size, ovoid, or subcrescentic, 

 oblique. The parotid glands, anteriorly contiguous to the supra-tym- 

 panic ridge, extend over the shoulders, a little obliquely downwards. 



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