130 CARCINOLOGICAL NOTES ; 



* 



for with the exception of this and one other species, every form is 

 assigned to a wrong genus. The genus Angasia is, as I have previously 

 shown, synonymous with the earlier Tozeuma of Stimpson. 



Evaxius tricarinatus n. g. et n. s. PI. I, fig. 1. 



A single imperfect specimen, lacking both chelipeds, forms the ba- 

 sis of this description. I should hesitate to describe it were its other 

 characters so well marked as to render it a very distinct and interest- 

 ing form. 



Cephalothorax small, compressed ; abdomen large and somewhat 

 depressed. Body everywhere with a sparse pubescence, among which 

 are interspersed larger hairs. Carapax with a median dorsal carina 

 extending from the "cervical suture" 3 as far as the eyes and termi- 

 nating anteriorly by a sharp tooth ; just behind this tooth occurs a 

 broad and shallow emargination. On either side of this median 

 carina is found a less conspicuous one extending from above the eyes 

 half way back to the "cervical suture;" its anterior, extremity like- 

 wise terminating in a tooth similar to that of the median carina. In 

 front of these carinae the carapax is strongly deflexed and terminates 

 anteriorly in a small triangular rostrum extending about half its 

 length, beyond the eyes. The anterior and inferior margins of the 

 carapax are smooth and unarmed. The basal joints of the antennulse 

 are hairy, the two distal ones being subequal. Flagella two, of equal 

 length, but the inner of smaller diameter; no spines or scales on the 

 basal joints. Antenna without a basal scale, the penult joint com- 

 pressed and over twice the length of the last joint; flagellum a little 

 longer than the carapax. External maxillipeds pediform, flattened 

 and extending to the extremity of the antennal peduncle. In the 

 specimen the first pair of pereiopoda had been broken off during life, 

 but were in process of restoration ; the chelae were didactyle, the fin- 

 gers being equal. Second pair of walking feet compressed ; carpus 

 and propodus subequal; the chelae well formed. Third and fourth 

 pairs also compressed, monodactyle, the propodus pectinate and 

 bristled beneath. Fifth pair smaller, subchelate. Pleopoda small 

 and inconspicuous. Lower margins of abdominal segments rounded. 

 Caudal lamellae broad with rounded extremities, each with a median 



3 This suture does not indicate the line of division between the head and thorax 

 as is usually stated. Those who may be interested will find a masterly exposition 

 of the meaning and significance of this line in the portions on the morphology of 

 the Crustacea with which Professor Dana begins his splendid work on the Crus- 

 tacea of the U. S. Exploring Expedition. 



