MUSEUM OF COMPARATIVE ZOOLOGY. 113 



width of the carapax. The distance between their extremities equals 

 four fifths of the greatest width of the carapax. The extremity of the 

 orbital sheath is armed with two spines, one before and one behind the 

 eye. The spine of the basal joint of the external antennas is rather small 

 and slender, and abdut one third as long as the rostrum. The ambulatory 

 feet are very slender. 



The measurements of a female specimen are : Total length of carapax, 

 0.90 ; breadth, excluding the spines, 0.G5 ; length of first pair of ambula 

 tory feet, 0.75 inch. 



It may be distinguished from all the species hitherto known by the 

 great size and prominence of the orbital sheaths. 



Off French Reef, April 3, 1869. Cast No. 1. 15 fathoms. 

 West of Tortugas, Jan. 1(3, 1869. Cast No. 9. 37 fathoms. 



Pericera septemspinosa nov. sp. 



Carapax oblong, strongly convex, pubescent ; antero-lateral and postero- 

 lateral sides concave. Dorsal surface armed with seven prominent spines, 

 one on the gastric, one on the cardiac, one on the intestinal, and two on 

 each branchial region. Rostrum about one fourth as long as the post-frontal 

 portion of the carapax, detlexed ; horns snbtriangular, acute, diverging, 

 curved, pointing outward. Orbits projecting, with a prominent, acute 

 prasocular and postocular spine. On the suborbital and subhepatic region 

 there are three spines, the posterior one of which is longest. There is a 

 small, slender, acute spine on the basal joint of the antenna?. Feet un- 

 armed. The pubescence of the body adheres strongly to rough objects 

 brought in contact with it, and notably to that of other specimens of the 

 same crab. 



Measurements of a male: Length of carapax, 0.33 : breadth, excluding 

 the spines, 0.25 inch. 



It differs from P. eutheca in its broader rostrum and less prominent 

 orbital sheaths; also in the spines on the subhepatic region, etc 

 West of Tortugas, January 16, 1869 Cast No. 4. 36 fathoms. 



Pericera cornuta H. M.-Edw. 



Cancer cornuta Herbst, Naturg. d. Krahhen u. Krebse, pi. lix, fig. 6. 



Maia taunts Lamarck, Animaux sans Vert., V, 242. 



Pericera cornuta II. Milne-Edwards, Hist. Nat des. Crust., I, 335 ; pi. xiv 

 bis, fig. 5. Illust. Cuv. Rcgne Anim., pi. xxx, fig. 1. Gibbes, Proc 

 Am. Assoc. Adv. Sci. 1850, p 172. Stimpson, Notes on N. American 

 Crust., p. 55. 



A young example, one inch long, of this well-known species, occurred in 

 rather dee]) water. It had previously been found only about low-water 



VOL. II. 8 



