412 William Morton Wheeler 



shaped, and carries four pairs of ovigerous appendages; the che- 

 lae are small and narrow. 



"Now it is found that in about 70 per cent of males infected 

 with Sacculina the body takes on to varying degrees the female 

 characters, the abdomen becoming broad as in the female, with 

 a tendency to develop the ovigerous appendages, while the che- 

 lae become reduced ( Fig. 5C). This assumption of the female 

 characteristics by the male under the influence of the parasite 

 may be so perfect that the abdomen and chelae become typically 

 female in dimensions, while the abdomen develops not only the 

 copulatory styles typical of the male, but also the four pairs of 

 ovigerous appendages typical of the female. The parasitized 

 females, on the other hand, though they may show a degenerate 

 condition of the ovigerous appendages ( Fig. ^D), never develop 

 a single positively male characteristic. On dissecting crabs of 

 these varying categories it is found that the generative organs 

 are in varying conditions of degeneration and disintegration. 



"The most remarkable fact in this history is the subsequent 

 behavior of males which have assumed perfect female external 

 characters, if the Sacculina drops off and the crabs recover from 

 the disease. It is found that under these circumstances these 

 males may regenerate from the remains of their gonad a perfect 

 hermaphrodite gland, capable of producing mature ova and sper- 

 matozoa. The females appear quite incapable, on the other 

 hand, of producing the male primary elements of sex on recovery 

 any more than they can produce the secondary." 



The following account is quoted from Pott's summary ('09) 

 of his own studies on the modifications induced in Eupagurus by 

 Peltogaster and of Smith's observations: 



"The difference between the sexes of Eupagurus is shown only 

 in a couple of external characters, the position of the generative 

 apertures (as in all Decapods) and the character of the abdominal 

 appendages. The abdomen of the hermit crab is furnished on one 

 side only with a few appendages, insignificant, but with definite 

 functions. It is in the female that we see the full development of 

 the appendage as a swimmeret with two equal branches, the inner 

 one provided with long hairs affording a secure anchorage for 



