THE YPSILOID APPARATUS OF URODELES. 257 



Cartilago ypsiloideS) present. Cartilago ypsiloides, absent. 



Amblystoma opacj/m, Spclerpcs bi tin ea tits, 



Amblystoma punctatnm, Spelerpes guttolineatiis, 



Amblystoma jeffersoniannm, Spelerpes porpliyriticus, 

 Amblystoma talpoidcum, Spelerpes longecandns, 



Salamandra macnlosa, Manc2t/us quadridigitatus, 



Salamandrina perspicillata. Pletlwdon cinereus, 



Plethodon erytlironotus, 

 Antodax lugubris. 



In those forms in which the cartilage is present it exhibits the 

 typical Y-shaped character, and is movably articulated to the 

 anterior edge of the pubis. In the species given in the right- 

 hand column there is no trace of the cartilage whatsoever. 

 These results show that the presence of a Cartilage ypsiloidcs is 

 closely correlated with the presence of lungs, although there 

 seem to be two exceptions, viz., Amblystoma opaciim and Sala- 

 mandrina perspicillata. The first of these, however, rests upon 

 an error, since the Amblystoma opaciim, like the others of its 

 genus, possesses large and well developed lungs, although 

 through the authority of Lonnberg ('96) this species has for sev- 

 eral years been placed among lungless forms. It is impossible 

 to say through what appearances Lonnburg was deceived, but 

 the presence of well developed lungs has been repeatedly demon- 

 strated by me through dissection and physiological experiment. 

 The most plausible hypothesis is that he was mistaken in his 

 species, an error extremely likely to occur in the study of this 

 group. 



Marked differences in the activities of lungless and lunged sal- 

 amanders when in the water, a subject which will receive full 

 discussion later, further corroborate the view that the function of 

 the ypsiloid cartilage is correlated with that of the lungs. In fact, 

 it was this difference in activity which first called my attention to 

 the difference in anatomy and led me to make an extensive study 

 of the ventral pelvic region of Urodeles. 



