CROCODILIANS, LIZARDS, AND SNAKES. 703 



minor divisions and genera of the Serpentes. The characters which I 

 have discovered in the hemipenis have added greatly to our resources 

 in the attempt to learn the relationships and hence origin of the mem- 

 bers of the Serpentes. 



In a broad way we may distinguish as leading types the following: 

 The smooth; the plicate, or flounced; the calyculate, or ruched; and the 

 disk-bearing. Any of these may have the sulcus spermaticus simple 

 or bifurcate, and some of them may have the middle i)art of the organ 

 spinous or not. The spines may extend to the apex so as to obliter- 

 ate the pattern and the total organ may be bifurcate or not. As regards 

 the indications of affinity presented by these types, it may be said that 

 the nearer we approach the Sauria the less spinous is the organ, 

 and the further away is the form the more, certainly will the ruched 

 structure prevail. The tendency to bifurcation is present in most 

 groups, but it is universal in but one suborder, the Solenoglypha, or 

 specialized venomous snakes. 



In the Oriental region we have the smoothest type of Colubroidea, 

 which includes the genera really allied to Galamaria, many of which 

 have had hitherto widely different positions in the systems. Owing to 

 tee scarcity of specimens of this type in American museums, I have 

 not been able to investigate them fully. The great Colubrine division 

 is remarkably constant in its undivided sulcus and abundant calyces. 

 In degenerate types the calyces become less numerous. The groove- 

 toothed Dipsadines have the same structure. Except one Australian 

 genus {Acanthophls) all the dis(;iferous types are neotropical and all 

 have a double sulcus. The other neotropical types with double sulcus 

 may be calyculate or spinous and they present a great variety of detail. 

 Here again the glyphodont and aglyphodont types are quite parallel 

 to each other. The structure in the water snakes is again different 

 and characteristic. The organ is feebly spinous from the base to or 

 near to the apex, possessing no calyces, disk, or transverse plica?, and 

 the prehensile function is maintained by one or a few large hook-shaped 

 spines at the base. In 1864 I referred several genera which had been 

 placed in the Calamarinte to the water snakes on account of the con- 

 tinuation of the hypapophyses to the tail. I was much gratified on 

 examining their hemipenes to find that they (genera Tropidodonium^ 

 Virf/lnia, and Haldea) present exactly the characters of the group to 

 which the vertebra' indicated that they should be referred. In like 

 manner I have been able to refer genera supposed to belong to the 

 Calamarinw to almost every natural division of the Colubroidea by 

 the study of the hemipenis. The old CalamariutTe of authors is snn])ly 

 an aggregation of burrowing or degraded forms of several natural 

 groups. 



The Natricine (water snake) group is connected with the groove- 

 toothed water snakes (Homalopsina'), and both of these groups pass 

 probably into the Lycodontine series, the typical forms of which the 



