1896.] NATURAL SCIENCES' OF PHILADELPHIA. 463 



I have examined the bemipenis in thirty species of the Iguanidse 

 of the following genera : Anolis, Xiphocercus, Polychrus, Basiliscus, 

 Ctenosaura, Cyelwa, Iguana, Corythophanes,Sauromalus, Crotaphy- 

 tus, Dipsosaurns, Sceloporus, Callisaurus, Holhrookia, Enyalioides, 

 Doryphorus, Microlophus, Uraniscodon and Phryrwsoma. These 

 differ in the bifurcation of the organ, varying from undivided 

 (Cyclura, Iguana) to deeply bifurcate (Anolis, Doryphorus, Micro- 

 lophus, Uraniscodon). Other differences are seen in the number of 

 welts and their surface structure, and the distribution and size of the 

 calyces. Thus the calyces extend to the base in Anolis, but are 

 confined to the apex in Crotophytus. They exist in series only in 

 Cyclura, Iguana, Ctenosaura, Corythophanes and Sauromalus. They 

 cover most of the organ in Sceloporus and Phrynosoma. The syste- 

 matic arrangement of the genera in accordance with the characters 

 is as follows : 



I. Calyces always present. 



A. Three welts, one opposite the sulcus sperraaticus and one 

 ^ parallel on each side of it transversely laminate : Cteno- 

 saura, Cyclura, Iguana, Corythophanes, Sauroma- 

 lus, Crotaphytus. 



B. Three welts ; one opposite sulcus, the others on each side 

 of sulcus converging to median welt, and enclosing spaces 

 with it ; surfaces calyculate. 



a: Median welt confluent proximad : Dipsosaurus, 

 Liocephalus, Phrynosoma. 

 a: a Median welt projecting free proximad : Callisau- 

 rus, HOLBROOKIA. 



C. No median welt ; lateral welt from sulcus : Sceloporus. 



D. A median, no lateral welts ; calyculate. • 



cc Not bifurcate ; welt wide : Enyalioides (calyces 

 coarse). 

 cc « Bifurcate ; welt long and narrow : Anolis (caly- 

 ces minute). 



E. No welts. 



cc Deeply bifurcate; calyces confined to branches: 

 Microlophus, Uraniscodon, Doryphorus. 

 s a: Shortly bifurcate ; calyces extending proximad of 

 branches : Basiliscus. 



II. No calyces or welts. 



cc Bifurcate ; surface coarsely wrinkled : Polych- 

 rus. 



