500 O. W. HYMAN 



abdomen fits tightly into its groove on the thorax. Its lateral 

 borders are beset with numerous straining hairs. The hairs 

 around the telson are numerous and brushy. 



The eyes (fig. 19) have now reached their adult condition. 

 They are bisegmented and the terminal segment bears the com- 

 pound eye facets over its distal and lateral faces. The eyes are 

 carried erected over the carapace in this stage, but may be lowered 

 into their imperfect orbits for protection. 



No changes have occurred in the first five pairs of appendages 

 except slight changes in the relative sizes of some of their parts 

 and a multiplication of the hairs on each. 



The first and third maxillipeds show no change of importance. 

 They are more hairy and some of their hairs have developed into 

 so-called 'comb hairs.' On the second maxilliped (fig. 73) the 

 gill and the epidodite are now developed, although both are 

 quite small. The gills present in this stage are as follows: a 

 podobranch on the second maxilliped; two arthrobranchs or 

 pleurobranchs between the third maxilliped and the cheliped; 

 two pleurobranchs at the base of the cheliped, and one pleuro- 

 branch at the base of the second period. 



In the female the chelipeds are not differentiated, but both 

 remain small with spoon-shaped extremities (fig. 78). In the 

 male, one of the claws is considerably enlarged, is thicker, and is 

 adapted to cutting and pinching (fig. 77). The spoon-shaped 

 chelae are especially adapted for scooping up the fine sand from 

 which the animals get their food. 



The abdominal appendages are now modified to form sexual 

 organs. In the male, the appendages of the first and second 

 abdominal appendages only are present. Each consists of two 

 segments. The appendage of the first segment is composed of 

 a rather broad basal portion and a rod-like distal segment. The 

 distal segment is grooved along its median border. The appen- 

 dage of the second segment is much smaller than that of the first, 

 but has the same enlarged basal segment and rod-like distal seg- 

 ment. The distal segment, however, is cylindrical. In the fe- 

 male, appendages appear on the second to the fifth segments. 

 Each is composed of a basal portion and two rami. Both rami 



