REPORT ON THE CRUSTACEA MACRURA. 59 



The body of the animal is tlorsally considerably depressed, so that the sharp lateral 

 margins which correspond with the branchial region in Panulirus, W'dlemccsia and 

 Ergon, are thinned out to an extent equalling that of some of the Brachyura, and the 

 cervical fossa, which in the Macrura is frequently so very conspicuous, and ends in a slight 

 notch, is absent in this species, while the lateral notch is deepened to a very considerable 

 extent, and widely separates the suborbital and hepatic regions from the branchial. The 

 pleon is also much depressed, and the. coxal plates on each side are extended outwards 

 rather than downwards, and the entire aspect of the animal suggests that it has, 

 through a series of generations, been compelled to live where it was necessary to extend 

 itself, under a constant heavy pressure, against some resisting body. 



The eyes are implanted in orbits that are deeply excavated in the dorsal surface 

 of the cephalon; the angles, more especially the external, are considerably produced, so 

 that the orbit makes about two-thirds of a circle, the margin of which is fringed with a 

 copious blepharis. The infero-anterior margin of the orbit also is excavated in the frontal 

 surface, so that a glimpse of vision might have been obtained beneath, when the eyes were 

 ensconced within the depth of the orbit. 



The first pair of antennae (PI. VIII. fig. C, b) possesses much of the character of those 

 of the Brachyura. The three joints of the peduncle are moderately long, and the terminal 

 flagella short, arising from the circumstance that the numerous articuli, more especially 

 in the primary branch, are extremely short and closely compressed together, so that the 

 membranous cilia are gathered together in a closely-arranged mass. At the base of the 

 first joint, on the upper surface, is a small tubercle, behind which the foramen, protected 

 by a bundle of small hairs, opens into the auditory chamber. 



The second pair of antennae (PI. VIII. fig. C, c) is of peculiar form, and characteristic of 

 this family. It consists of five joints. The first or coxal joint is closely fused with the 

 ventral portion of the cephalon, and carries on the inferior surface a phymacerite, which 

 is planted so near the oral aperture, that it is covered and protected by the organs 

 attendant on the mouth. The somite that carries this pair of antennae is visible at 

 the base of the first pair on the upper or dorsal surface in the form of two small plates 

 (PI. VIII. fig. C) dove-tailed into the frontal margin on each side of what in a normal 

 condition would be the rostrum ; the anterior margin of the carapace and the upper 

 surface of the first antennal somite appear to be fused, and by the generally depressed 

 character of the animal, are brought into a .horizontal position in the same plane. 

 The posterior margin dips beneath the anterior margin of the carapace, and passing 

 laterally, forms the floor of the orbit, whence it continues upwards to the orbital 

 notch, thence outwards, forming the great antero-lateral angle of the carapace, and, being 

 reflexed on itself, returns and unites with the ventral walls of the coxal joint of the 

 second pair of antennae. The second or basisal joint articulates with the first, with very 

 little movement, and impinges very closely against the external lateral walls of the first 



