Order 1. DECAPODA. " 419 



species of our climate [known in the fish-shops under the name of the Spiny Lobster] is found during the winter 

 in deep water, approaching the coast only at the return of the spring. It prefers rocky situations. It then lays 

 its eggs, which are extremely numerous, minute, and bright red. According to Risso, they again breed in August. 

 The different species are found in the seas of temperate and intertropical zones. The carapax is rough, and 

 strongly armed with sharp points or teeth, especially in front. Their colours are varied with red, green, and 

 yellow. The tail is often banded, or marked with eyes. The flesh, especially of the females before and during the 

 breeding season, is greatly esteemed. 



The common English typical species, Palinurtis quadricornis, Fabr. (Antaeus elephas, Leach), is of a large size; 

 and, when loaded with eggs, weighs twelve or fourteen pounds. It is found upon the French coasts as well as our 

 own. It is very abundant on the shores of the Mediterranean, and has also been found in the fossil state in Italy. 



The third section, Astacini (Latr.), is distinguished from the preceding in the form of the two fore- 

 legs, and often also in that of the two following pairs, which terminate in claws with two fingers. In 

 some, the two or four hind-legs are much smaller than the preceding, in which respect they approach 

 the Anomala ; but the fan-like swimmeret at the extremity of the tail, and other characters, remove 

 them from that section. The thorax is narrowed in front, which is produced into a beak or pointed 

 muzzle. 



The first subsection, Galathade^e, have, as well as the preceding Macroura, four pairs of false legs. 

 The intermediate antennae are elbowed with two filaments, which are clearly shorter than their pe- 

 duncle ; and that of the lateral antennae is never furnished with a scaly plate. The two fore-legs are 

 alone terminated by a didactyle claw, which is often very broad and flattened. The terminal segment 

 of the tail is bilobed, at least in the majority. 



Those species which have the two hind legs much more slender than the preceding, filiform, folded, and useless 

 in crawling, are the two following genera. Galathea, Fabr., having the tail extended, the thorax nearly ovoid or 

 oblong, the intermediate antennae exposed, and the claws long. The upper surface of the body is generally trans- 

 versely wrinkled, spinose, and ciliated. 



Cancer strigosus, Linn., and C. rugostis. Pennant, are two common species on our English coasts. G. gregaria, 

 Fabr. (forming Leach's genus Grimotea), is of a red colour; and was discovered by Sir Joseph Banks in his voyage 

 round the world, abounding in some parts of the ocean in such vast quantities that the surface of the water ap- 

 peared as if saturated with blood. [Gray, in his Zoological Miscellany, and M. Edwards, have described many 

 species of this genus.] 



Porcellana, Fabr., forms, amongst the Macroura, a remarkable exception in respect to the structure of the tail, 

 which is bent under the body, as in the Brachyura. It differs from Galathea in its broader outline, the carapax 

 being often suborbicular, or square. Tlie claws are triangular, the basal joints of the outer foot-jaws are dilated, 

 and the body is very flat. They are of small size, slow in their movements, and are distributed in all the seas, 

 hiding themselves beneath stones on the shore. Some species have the claws very large, villose, and very much 

 ciliated : amongst which is the common English species Cancer platycheles, Pennant, of which the outside of the 

 claws is alone hairy, aud the thorax naked and rounded. Others have the claws naked, including Cancer hexapug, 

 Linn. 



Monolepis, Say, seems to be intermediate between Porcellana and Megaloptis, Leach ; (Macropa, Latr.) The 

 latter differs from the preceding in having the hind pair of legs similar in form and function to the preceding 

 pairs ; the body much more thick and raised ; the eyes large ; the lateral plates of the anal swimmeret composed 

 of a single piece ; and the abdomen extended, narrow, and merely curved beneath at its extremity. Four species 

 are known : three found in the European seas, and the other in the Indian Ocean. [Dr. J. V. Thompson, in his 

 Memoir published in the Philosophical Transactions, has expressed his opinion that these animals are the young 

 of a Brachyurous Crab. The abdomen is, however, furnished beneath with a double pair of false legs, as in the 

 Macroura ; and the tail is terminated by a swimmeret. The branchias are arranged, however, as in the Brachyura. 

 M. Edwards considers them as the young of some of the Anomoura.] 



The second subsection (Astacini proper) comprises taose species which have four pairs of fahe [sub- 

 abdominal] feet ; the intermediate antennae straight, or nearly so, porrected, and terminated by two 

 filaments as long as or longer than the peduncle, and which (except in Gebia) have the four or six fore- 

 legs terminated by a didactyle hand. The tail is always extended. The two hind-legs never much 

 slenderer than the preceding, nor bent backwards. The peduncle of the lateral antennae is often pro- 

 vided with a scale. Some species, as in some of the following sections, live in fresh water. 



Amongst those which have not more than the four fore-legs terminated by two fingers, the lateral antennas not 

 furnished with a scale at the base, the outer piece of the lateral plate of the swimmeret without any transverse 

 suture, and which are marine, hiding themselves in burrows which they form in the sand, are the genera Gebia, 

 Leach [comprising a small British species], and Tkalassina, Latr. [a singular genus from the East Indies] ; and 

 in both of which the immoveable finger of the claws is very short, whilst it is as long as the moveable finger in 

 the genera Callianassa, Leach, in which the fore-claws are very miequal both in their size and form (including a 

 single species, C. stibterranea. Leach, found on the English and French coa&ts) ; aud Axius, Leach, in which the 



