SPERM-TRANSFER ORGANS IN CAMHAROIDES. 267 



the limbs ///, //'and V. Each plate expands toward the limbs 

 as a lateral wing, W, each plate is also modified in its central 

 part. Between the third limbs the central part shows a rounded 

 boss and an anterior prolongation ; between the fifth limbs there 

 is only a boss ; between the fourth limbs the median part of the 

 plate is prolonged backward not as a boss but as a large expanse, 

 the annular plate, An. This annular plate is subdivided into an 

 anterior part, An, somewhat convex from side to side and a pos- 

 terior part which is hollowed out as is poorly shown in Fig. 14. 



The hollowed posterior part of the annular plate rises up dor- 

 sally at an angle with the horizontal anterior part. 



The median depression is quite shallow and neither in surface 

 views nor in sections is there any slit or internal pocket such as 

 is characteristic of the annular plate of the genus Cambanis. 

 Thus while in both Cambarus and Cambaroides there is an 

 annular plate only in Cambanis is it provided with an internal 

 cavity. It is the internal cavity in the annular plate that is filled 

 with sperm. In these specimens of Cambaroides no sperm pocket 

 is found. 



In the male Cambaroides, Fig. 12, there is also an annular 

 plate between the fourth limbs but it lacks the hollowed posterior 

 part that is found in the female. 1 



In a specimen of Cambaroides similis the posterior part of the 

 annular plate is less sharply hollowed out than in C. Japoniciis. 



The use of these various male and female parts can, as yet, only 

 be inferred from comparisons with the organs of Astacus and of 

 Cambanis whose use has been observed. But in applying the 

 male to the female we are led to imagine that the stylets may de- 

 posit spermatophores between the fourth and fifth limbs. 



1 In the individual male figured here there is an abnormal pair of structures that 

 simulate the openings of oviducts. In the female the oviduct openings, Fig. 14, 

 are large elliptical membranous areas upon the bases of the third limbs. In the male 

 the openings of the defferent ducts are more elevated areas upon the bases of the 

 fifth limbs, Fig. 13. There is thus both a difference in position and in character 

 between the male and the female openings. The abnormal openings upon the third 

 legs of the male figured in 12, are like female openings both in position and character 

 though they are smaller than normal and the one upon the right of the animal i s 

 especially small fsee also Fig. 2). This then seems to be a case of partial mixture 

 of sex organs such as have been described in both Astacus and Cambarus (see Am. 

 Nat., 1909). 



