82 ON THE JSTRUCTUllES AND DISTRIBUTION OF THE 



suture, and is extended in an arch over the temporal fossa. The anterior ossification 

 of the coccyx is appHed by its axial portion beneath the axis or centrum of the sacral 

 vertebra, and becomes consolidated with it shortly after its commencement, furnishing 

 a structure not rare among burrowing Anura. This character is maintained in the 

 descending scale by Pelobates, Didocus, Scaphiopus and Spea, though none of these 

 have the temporal fossa overarched. Cultripes, with Pelobates and Didocus, exhibit 

 an ossified basal xiphisternal piece, while in all below it is cartilaginous, as in most 

 Arcifera : the extreme position of the former is also maintained by the obliteration of 

 many portions of the auditory apparatus. The succeeding forms Scaphiopus, Spea 

 and Helioporus, resemble the first group in the toad-like form, and in the strong 

 cuneiform shovel and webbed feet, but in the last the usual bicondyloid articulation 

 of coccyx brings us within the limits of the Cystignathidte, and with Spea, an 

 incomplete cranium marks a descent. The more elongate Cystignathid form of Chiro- 

 leptes maintains the Scaphiopod foot, with a strong cranium, while in the same family 

 the superficially similar Hyperolia exhibits no longer the cuneiform shovel, or any 

 true mark of affinity. 



The distribution of the species of the family is as follows : 



The inferior dermal attachments of seven species of this family are as follows : 



Didocus calcaratus ; belly more than half attached. 



Pelobates fuscus ; from half to two-thii'ds attached ; same in larva, with long tail. 



Femur one line below. 

 Scaphiopus holbrookii ; free only opposite sternum ; thigh attached only below on 



basal half. 

 Scaphiopus couchii. Triangular free area to middle abdomen. 

 Spea hammondii, very wide lateral inferior attachments, which do not meet till 



femora. 

 Spea bombifrons. Belly with a free median band ; femoral lines, below and above 



behind. 

 Spea multiplicata. A free dorsal line, very narrow in front, but wide as ilia behind ; 



abdominal area with a broader free space. 



