1895. PROCEEDINGS OF THE NATIONAL MUSEUM. 363 



segment of the abdomen, slightly curved at the ti]) in tlie adult. Abdo- 

 men of female (Plate XXVII, fig. 7) with fifth segment much narrower 

 distally than proximally, and shorter than sixth. Costa' of manus 

 coarsely granulate. The three carpal spines mentioned by Ordway 

 (he had but one specimen) are present in some of the smaller speci- 

 mens, but are not equal, and in older specimens the anterior two are 

 more or less rudimentary. 



Small specimens are less convex and more prominently areolated 

 than the adult. The large frontal teeth are wider. A single medium- 

 sized individual taken by the Ilassler ;it Panama (Mus. Comp. Zool.) 

 has unusually long spines, between three and a half and four times the 

 length of the next tooth. 



Size. — The largest male is about 4f inches wide. The largest female 



is 4| inches; one bearing eggs is 3| inches wide, and has the lateral 



spine strongly curved forward. Most of the vspecimens examined are 



small. 



Measurements of Callinectes arcuatus. 



Specimens have been examined from the following localities: 



Lower California and Gulf of California, U. S. Fish Commission str. Albatross, 

 1889: San Bartolonie Bay, Lower California (No. 15433, U. S, N. M.); Con- 

 ception Bay, mouthof RioMulege(No. 15432, U. S. N. M.); Algodones Lagoon, 

 Mexico (many small specimens, No. 15431, U. S. N. M.); Horseshoe Bend, 

 Colorado River (No. 15434, U. 8. N. M.). 



Cape St. Lucas (type locality); .John Xantns (Mns. Comp. Zool.). 



Guaymas, Mexico; H. F. Emeric (No. 14854, U. S. N. M.). 



Acapnlco, Mexico; Hassler Expedition (Mus. Comp. Zool.). 



Gulf of Fonseca; J. A. McNiel (Mus. Comp. Zool.). Types of C. duhia, Kingsley. 



Panama (type locality of C. pleuriticiis) ; Received from Mus. Comp. Zool. (No. 

 18511, U. S. N. M.). 



CaUmectes arcuatus and G. dancv are perhaps more closely related than 

 any other two species of Callinectes. The front of C. arcuatus has the 

 median pair of teeth sharper and more prominent, the lateral pair 

 broader, and the submedian tooth shorter than in C. damv. The antero- 

 lateral margin is moi-e arcuate, and its teeth directed forward instead 

 of outward. Terminal segment of abdomen in male shorter than in 

 C. dana', and appendages of first segment longer, and curved instead 

 of straight at the tips. 



CALLINECTES TOXOTES, Ordway. 

 (Plates XXI; XXIV, fig. 9; XXV, fig. 9; XXVI, fig. 9; XXVII, fig. 8.) 



Callinectes toxotes, Ordway, Boston Journ. Nat. Hist., VII, p. 576, 1863. 

 Callinectes toxotes, A. Milne-Edwards, Crust. Reg. Mex., p. 227, 1879 (variety of 



Callinectes diacanthus) . 

 Callinectes rohiistus, A. Milne-Edwards, Crust. Reg. Mex., p. 227, 1879 (variety 



of Callinectes diacanthus). 



