LlEMODIPODA. 429 



the order Isopoda), namely, the Crevettines and the Ilyperines, the former divided into the saltatorial 

 and ambulatory species. Some new genera were added, especially in the singular family of the ilyperines. 

 Pleryqocera, Latr., and some other genera, he considers not snfficietitly studied, and consequently of 

 doubtful cbaracter and situation. Apseudes, lone, Anceus, and Praniza, he also regards a> isopodous. 

 Various ad litional genera have also heen established by M. Guerin de Mencville, in the Magasin <te 

 Zoologie, especially amongst the Ilyperines, and which are accompanied by figures and generic details. 

 Dr. Templeton has described some curious minute species from Mauritius, in the Transactions of the 

 Entomological /Society. Still more recently I have received from M. Kroyer, the Danish naturalist, a 

 memoir upon the Amphipoda of Greenland, published in the last part of the Copenhaijen Transactions. 

 Ratbke has described many new species, and some new genera from the Caspian Sea, in the last volume 

 of the Petersburg Memoirs, and Professor Owen has described some interesting species brought home in 

 one of the late Polar expeditions. One of the most remarkable of the subgenera established, is that of 

 Orio of A. Cocco, described in the Giornali di Scienze, Sfc, per la Sicilia, for November 1 833, which has 

 been overlooked by Crnstaceologists, and in which the maxillary palpi are exceedingly slender, as long 

 as the body, and 4-jointed.] 



THE FOURTH ORDER OF CRUSTACEA, 



LCEMODIPODA,— 



Comprises the only Malacostraca with sessile eyes -which have not distinct branrhine attached 

 at the extremity of the body, which are nearly destitute of a tail, the hind pair of legs being 

 attached either at the extremity of the body or to a segment, followed by one or two very 

 small joints. They are also the only species in which the two fore-legs, which correspond 

 with the second foot-jaws, form part of the head. 



All the species have four setaceous antenna, implanted on a peduncle of three joints ; 

 mandibles destitute of ]ialpi ; a vesicular body at the base of at least four of the pairs of legs, 

 commencing with the second or third pair, including those of the head. The body, generally 

 filiform or linear, is composed (including the head) of eight or nine segments, with several 

 small appendages in the form of tubercles at its posterior and inferior extremity. The legs 

 are terminated by a strong hook; the four anterior, of which the second pan* is the largest, arc 

 always terminated by a monodactyle claw. In some, the four following are more Blender, 

 with t'.wcr articulations, without a terminal hook, or are rudiinental and in no manner lilted 

 for the ordinary uses. 



The females carry their eggs beneath the second and third segments of the body, in a pouch 

 formed of scales closgly applied against each other. 



All these Crustacea are marine. M. Savigny considers them as approaching the Pycno- 

 gonides, and as forming, together with them, the passage between the Crustacea and 

 Arachnida. In the first edition of this work, they formed part of the [sopodous order, namely, 

 the section ( '\ stibranchiic. 



Thev may be considered as forming a single genus, for which, on account of its priority, the name of 



Cyamus (Latr.) — 



should lie retained. 



Some of the-' (forming a first section named 1'iliformia, Latr.) have the bdflj long and very slender 

 or linear, with the segments longitudinal; the legs also long and very slender, and the terminal Hit- 

 nient of the antenna; composed of minute joints. 



They are found amongst marine plants, creeping along in the same waj as the I r or Looper* 



caterpillars, bending themselves often back with great rapidity, and applying their anteni irioua 



parts of the body. In swimming they bend the two ends of the body downwards. 



