ERYONICUS C^CUS. HI 



gastric region arranged in a longitudinal series behind the orbital sinus, one 

 at the bifurcation of the cervical ridge, and one at the anterior end of the 

 anterior branch of the cervical ridge. The subdorsal or branchial ridge of 

 each side bears five spinules, and there is one spinule on the branchial area 

 between the median and branchial carina?. The lateral carina, which runs 

 from the external angle of the orbit to the posterior margin of the carapace, 

 and is homologous with the lateral margin of the carapace in Poli/cheles and 

 WiUcmoesia, bears sixteen spines arranged thus : 6 — 3 — 7 ; of these the last 

 four are the largest. Below this lateral carina there are two longitudinal 

 ridges on each side of the carapace, the upper of which extends from the 

 outer side of the base of the second antenna almost to the hind border of 

 the carapace, and is spinulose along the anterior third of its course ; the 

 lower carina starts on the margin of the pterygostomian region one third 

 of the way from the anterior end of the carapace, curves outward and 

 extends back to the posterior margin of the carapace ; this carina is very 

 prominent posteriori}', and bears five spines, decreasing in length from the 

 first to the fifth, and followed by small denticles ; the anterior spines in this 

 series are the largest on the body ; on the line of this ridge the carnpace is 

 bent sharply inward and becomes horizontal. Tlie internal orbital angle is 

 furnished with a minute spine not in advance of the rostrum. The external 

 orbital angle has a strong- spine, the first of ihe lateral ridge. The orbital 

 sinus is deep, and its posterior or blind end is broad and rounded. The 

 ophthalmic lobes are armed with an outward-turned spine on their front 

 margins. 



The abdomen is adorned with five longitudinal rows of spines, one 

 median and two pairs lateral ; the median or dorsal row is made up of 

 one spine on the first abdominal somite, two on tlie second, third, fourth, 

 and fifth, one on the sixth, and two on the proximal end of the telson; of 

 the two dorsal spines on the second, third, fourth, and fifth somites, the 

 anterior one is the longer, and is connected with the minute posterior one by 

 an elevated ridge ; the single dorsal spine of the sixth somite is sharp and 

 erect. The upper of the two Interal abdominal rows consists of a single spine 

 just above the pleura of each somite from the second to the sixth, while 

 the lower lateral row consists of one small spine on the upper portion of the 

 pleune of the second to the fifth somites. The pleurae of the first abdominal 

 somite are small, turned forward, and articulated with the hind part of the 

 carapace ; the second, third, fourth, and fifth pleurte are rounded, their mar- 



