60 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



thorax, antennse short, never more than one pair of feet chelate, 

 abdomen of the male narro\yer than that of the female. 



They are divided into four tribes, Cyclometopa, Ox5^r- 

 hynca, Catometopa, and Oxystomata. The three 

 first each have several representatives, while the last has an occasional 

 species in this vicinity. 



(Tribe) CYCLOMETOPA. 



The C y c 1 m e t o p o u s, or Cancroid, crabs can be de- 

 scribed in brief as follows: the carapace is usually broader than 

 long, arched in front, and bears no rostnam; the epistome is short. 

 Its three families, C a n c r i d se , P i 1 u m n i d se , and P o r t u - 

 n i d SL', have representatives in Rhode Island and include a large per 

 cent, of the most common crabs. 



(Family) CANCRID.E Latreille. 



This family is characterized by longitudinally folding antennse and 

 by long outer maxillipeds which overlap the epistome. One genus, 

 Cancer, is common in this vicinity. 



(Genus) CANCER Linnseus. 



Cancer is distinguished from the other genera in having its 

 buccal cavity completely closed by the outer maxillipeds. We find 

 two species, C. b o r e a 1 i s and C.irroratus. 



Cancer borealis Say. "Jonah Crab." 



Plate I. Figure 1.* 

 Cancer borealis Say. Verrill and Smith, 1874. 



* The figures copied were taken as loUows; 



Figures 1, 2, 9, 25, 26, 27, from United States Fisli Commission Reports. 

 Figures 6. 13, 15, from Rathbun's Invertebrates. 

 Figures 3, 4, 5, 8, from Benedict & Rathbun. 

 Figure 12, from Dekay. 

 Figures 16, 17, from Mayer. 

 Figures 16 and 19, from Paulinier. 

 Figures 7 and 21, from Verrill & Smith. 

 • Figures 28, 29, 30, 31, 32, from Birge. 

 Figures 33, 34, 35, 36, and 37, from AVilHamson. 

 The others were taken from specimens by H. D. Clough, who did all the photographic work. 



