REPORT ON THE CRUSTACEA MACRURA. 309 



Aristeus, Duvernoy. 



Aristeus, Duvernoy, Ann. d. Sci. Nat., torn. xv. p. 101, 1841. 

 Funchalia, Johnson, Proc. Zoo]. Soc. Lond., p. 895, November 28, 1876. 



Body laterally compressed. Surface generally rigid, except the inferior portion of 

 the branchial region, where it is soft and membranous. 



Carapace laterally and posteriorly produced. Frontal margin produced to a lono- 

 rostrum. 



Pleon having the first somite transversely divided, the anterior division of the dorsal 

 surface underlies the carapace, the posterior being connected with the coxal plate, which 

 anteriorly overrides the postero-lateral margins of the walls of the carapace. 



The ophthalmopoda are uni-articulate and support a small tubercle on the inner side. 



The first pair of antennae has the peduncle long ; the first joint is but slightly ex- 

 cavate to receive the ophthalmus, it has no prosartema, or only a small process tipped 

 with hairs, but carries a well developed stylocerite on the outer side ; the second joint 

 is generally long and subcylindrical, and the third joint is short, and carries two flagella; 

 one, attached near the base of the joint on the outer and upper side, is short, longi- 

 tudinally flattened, concave below and convex above, while the other, attached to the 

 extremity, is long, slender, and cylindrical. 



The second pair of antennas has the several joints of the peduncle freely articulating 

 with each other and with the metope. The first or coxal joint carries a well-formed 

 phymacerite on the inner side ; the second or basisal joint carries a large and broad 

 scaphocerite, which is double-jointed at the base on the under side so as to permit of a 

 downward movement, and is strengthened on the outer side by a rigid margin that 

 terminates anteriorly in a sharp tooth ; on the outer side the lateral movement is 

 checked by a small disk-like plate attached to the second joint, and on the inner and 

 upper distal surface is a short, blunt, tooth-like process that is lodged in a depression 

 formed on the under side of the first pair of antennae, and prevents a too great upward 

 and inward action ; the third, fourth, and fifth joints, which are the homotypes of the 

 ischium, meros, and carpos of the true legs, carries at its extremity a long flagellum. 



The epistoma is anteriorly produced to a more or less important rostriform point in 

 the median line, and supports posteriorly the cheiloglossa, the labial portion of which 

 overrides the mandibles and meets the metastoma posterior to them ; the glossal process 

 passes into the oral cavity and lies anterior to and fills the space between the mandibles. 



The mandibles are powerful organs, and have- the molar process larger than the 

 incisive, whde the synaphipod consists of two narrow joints which do not reach beyond 

 the base of the second pair of antennae. When the oral appendages are examined 

 in situ, the psalisiform blades of the mandibles are seen to overlap each other and 

 resemble " a pair of long sickle-shaped shears, which cross each other from opposite sides 



