GENERA OF THE ARCIFEROUS ANURA. 71 



Do., posterior fourth or fifth abdomen attached ; gracilis, speciosus, pantherinus. 

 Lateroventral attachment very broad, leaving but narrow free abdominal space : B. 



coniferns, quercinus, intermedins, punctatus, alvarius, diptychus. 

 Ventral integument attached : B. coccifer, insidior, viridis, kelaartii (posterior half 



attached.) 



A considerable variety is exhibited by the families of the Arcifera. In the genera 

 of Discoglossida3 examined (Discogiossus and Bombinator) the attachments are as in 

 Ranidse, except the absence of the coracoid septum, as in Dactylethra. On the con- 

 trary, in the Scaphiopodidse, the integument is more or less entirely adherent above 

 and below. The greater number, as well as typical forms of Hylidae, add to the 

 Raniform arrangement a close areolar attachment of the abdominal skin, while it is 

 characteristic of many species of CystignathidiB to possess one or two transverse, 

 simple posterior abdominal septa. For the many variations and exceptions, see 

 under the respective families. 



Of the Aglossa, Dactylethra lacks the coracoid, and inferior femoral attachments ; 

 there is a double or treble but not wide lateral adhesion low down, which may be a 

 combined dorsolateral and dorsoventral, or broad dorsoventral only. In Pipa all the 

 attachments are wanting, except two closely approximated lateral lines, and a supe- 

 perior posterior and anterior inferior femoral. 



The species of Arcifera, so far as known, exhibit some peculiar structures during 

 the breeding season ; either an extension of the natatory membrane, or the develop- 

 ment of corneous plates or spurs, as aids to prehension. There is more variety and 

 efficiency displayed in this point than among the Bufoniformia, but is in especial 

 contrast to the apparent absence of all but the weakest modifications among the 

 Raniformia. It is perhaps in compensation for the structure of the sternum, whose 

 lateral halves being movable, offer a slighter basis of resistance for the flexor and 

 extensor muscles of the fore limbs. 



In the Discoglossidge, Bombinator extends the natatory membrane in the male, but 



« 



does not develope horny plates. In Discogiossus two file-like oval plates cover the 

 superior surfaces of the short second digit, and the tubercle-like first, or thumb, which 

 is here developed as in no other anurous batrachian. Dermal rugosities on the upper 

 and under surfaces, including the gular region, are armed with corneous tips, as in 

 Telmatobius. No peculiarity has been noticed in Alytes. The Asterophrydida3 are 

 unknown. 



In Pelodytes file-like plates are developed, one on the second and one on the third 

 digit, one much larger on the forearm, one slightly smaller on the inside of the hu- 

 merus, and a small one on each side of the breast. 



Among SoaphiopodidfB the American species develope elongate lamince on the 



