PROCEEDINGS OF THE NATIONAL MUSEUM. 



351 



S. I. Smith, to examine a number of specimens in the Museum of Com- 

 parative Zoology of Harvard University and the Peabody Museum of 

 Yale University. I am indebted to Prof. C. C. Nutting- for i)ermissiou 

 to notice a specimen of G. dance from Cuba, collected by the Bahama 

 expedition of the State University of Iowa in 1893, and owned by 

 that institution. The approximate number of specimens of each spe ies 

 examined is as follows : 



Specimens of Callinectes examined. 



Only in working over a large amount of material is it possible to 

 judge whether the characters separating nearly related forms are 

 invariably coexistent, or whether they are modifications dependent on 

 environment, or simply individual variations. In the present case I 

 have been able to verify Ordway's classification, which was necessarily 

 based on a limited number of individuals. 



The valne of the differentiation of the generative organs in deter- 

 mining species, has for some time been recognized. It is well exempli- 

 fied in Callinectes. In C. sapidus, our common edible species, and the 

 only species north of Cape Hatteras, the appendages of the first abdom- 

 inal segment in the male reach as far as the tip of the last segment. 

 This is also the case in C. bocourti, of the tropical Atlantic, and C. toxotes 

 from the Pacific. In C. arcuatus and C. bellicosus of the west coast, 

 they reach or nearly reach the terminal segment, but not the extremity; 

 while in C. ornatus, C. dance and C. tumidus, they stop at the middle of 

 the penultimate segment, and in C. tumidus are curved at the tips. In 

 G. larvatns the appendages are noticeably short, reaching slightly 

 beyond the proximal end of the penultimate segment.' 



These variations in the length and form of the appendages are 

 accompanied by other diflt'erences. such as the shape and sculpture of 

 the carapace, the outline of the front and lateral teeth, the length of 

 the lateral spine, the granulation of the chelipeds, and the form of the 

 abdomen in both sexes. These differences are specific. In species 

 where tlie appendages are similar in length and position, no confnsion 

 need arise, owing to the other widely different characters possessed by 



'Broccbi (Aiiu. Sci. Nat., Zool., (6) II, 1875) claims to have examined a large luiin- 

 ber of specimeus of "Neptitiius diacanthus" from widely diftereut localities, aud liiids 

 only two distinct forms of appendages, long aud short, which are coincident with 

 only one other character, the outline of the front. He suggests the formation of two 

 species based on these characters. 



