414 



CRUSTACEA. 



The third section, Quadrilatera, have the carapax nearly square, or heart-shaped, with the front 

 generally elongated and deflexed, forming a kind of hood. The tail is composed of seven segments in 

 both sexes, the joints being distinct throughout the entire breadth of the tail. The antennae are 

 generally very short. The eyes are generally placed upon long peduncles. Many species reside in the 

 ground, forming burrows for their retreats, and some frequent fresh water. They are able to 

 run very fast. Some of these species have the carapax somewhat heart-shaped [thus nearly resembling 

 some of the Arcuata], with the front margin strongly toothed, including the genera Eriphia, Lat., 

 Trapezia, Lat., and Pilumnu-s, Leach, in which last the claws are of unequal size. 



The Thelphusce, L;it, have the lateral antenna; shorter than the ocular peduncles, and few-jointed. The carapax 

 is nearly of a cordate truncate form, [but broader behind than in the preceding]. There are several species of this 

 genus, which reside in fresh water, but being able to exist for a considerable time out of their native element ; 

 one noticed by the ancients occurs in the south of Europe ; it is the Cancer fluviatitis, Belon. It is often repre- 

 sented upon the ancient Greek medals. The Greek monks eat it uncooked, and it forms a common article of food 

 in Italy during- Lent. Delalande and De Latour discovered two other species, one in the south of Africa and the 

 other in the mountains of Ceylon. [I have described and figured another species, under the name of T/ic/p/tusa 

 cunicviaris, discovered by Col. Sykes, in the ghauts of the Deccan, where it occurs in great abundance, and of 

 which Bishop Heber thus speaks in his Journal :—" All the grass through the Deccan generally swarms with a 

 small land-crab, which burrows in the ground, and runs with considerable swiftness, even when encumbered with 

 a bundle of food as big as itself; this food is grass, or the green stalks of rice, and it is amusing to see the crab 

 sitting, as it were, upright to cut their hay with their shr.rp pincers, and then waddling off with their sheaf to their 

 holes, as quickly as their side-long pace will carry them." Col. Sykes found them on the table lands at an eleva- 

 tion of nearly 4000 feet above the sea, and as they are met with of all sizes, he believes that there productive pro- 

 cess is completed without the Crab having to undertake any annual journey to the sea, their migrations having 

 never been noticed.— Trans. Ent. Soc, vol. i.] To this section also belong other species of Land Crabs, composing 

 the genera Gelasimus, Ocypoda, and Mictyris. The first of these genera has the carapax solid, and nearly quadri- 

 lateral, but rather broader in front ; one of the claws is generally much longer than the other, the fingers of the 

 smaller claws being spoon-shaped. The animal closes the mouth of its burrow, which it makes near the shore, 

 with its larger claw. These burrows are cylindrical, oblique, and very deep, each having a single inhabitant. It is 

 the habit of this Crab to hold up the large claw in the front of the body, as though beckoning to some one, 

 whence they have obtained the name ot Calling Crabs. The species of Ocypoda has the eyes extended along the 

 greater length of the foot-stalks. Their claws are also unequal, but not to the same extent as in the Gelasimi. 

 During the day they sit in their burrows, venturing forth only after sun-set. The type Cancer cursor, Linn., inha- 

 bits Syria and Northern Africa. Other species of Land Crabs are of a truncate cordate form, with the shell rounded 

 and dilated at the sides. They inhabit tropical cbmates, and are called by the inhabitants tourlouroux, painted 

 Crabs, land Crabs, violet Crabs, &c, which names seem to be applied indiscriminately. There are few travellers 

 who have not mentioned their habits, often mixing up much fiction in their accounts. They pass the greater part 

 of their lives in the earth, hiding themselves by day and coming abroad only at night. Sometimes they frequent 

 cemeteries. Once a year, as the period for depositing their eggs draws near, they assemble in numerous com- 

 panies, and following the most direct line, seek the coast without permitting any obstacle to intercept them in 

 their way ; after laying their eggs [in the water] they return, greatly enfeebled. It is said that they close the 

 mouth of their burrows at the period of moulting, after which operation, and whilst still soft, they are reckoned 

 a great delicacy. These species compose the genera Uca, Latreille, (type Cancer uca, Linn., South America), and 

 Gecarcinus, Leach, (Cancer ruricola, Cuv., &c.) 



Another interesting group constitutes the genus Pinnotheres, Latr. These are of very small size [of which 

 there are several native species, named pea-crabs], and which reside, during a portion of the year at least, inside 

 various bivalve shells, such as muscles, &c. The carapax of the females is suborbicular, very thin and soft ; 

 whilst that of the males is firmer and nearly globular, and rather pointed in front ; the legs are of moderate 

 length, and the claws of the ordinary form ; the tail of the female is very ample, and covers the whole of the 

 underside of the body. The ancients believed that the Pea-crab lived upon the best terms with the inhabitant of 

 the shell in which it was found ; and that they not only warned them of danger, but went abroad to cater for 

 them. The type is the Cancer Pisum, Lin., and Leach has investigated the species in his Malacostraca Podo- 

 pthalma Britannica ; [but this author has given the males and young as distinct species. See further J. V. Thomp- 

 son's Memoir on this genus in the Entomol. Mag., vol. hi.] 



The section consists of several other well-marked genera, such as Grapsus, Lamarck, Plagusia, Latr., &c. 



The fourth section, Orbiculata, have the carapax either somewhat globular, or rhomboidal, or ovoid, 

 and always very solid ; the ocular peduncles are always short, or but slightly elongated ; the claws of 

 unequal size, according to the sexes, those of the males being the largest ; the tail never consists of 

 seven entire segments ; the oral cavity is gradually narrowed towards its superior extremity ; and the 

 third joint of the outer foot-jaws is always in the form of a long triangle ; the posterior legs resemble 

 the preceding, and none of them are very long. 



Corystes, Latr., has the carapax of an ovoid-oblong form, with the lateral antenna; [nearly as long as the body], 



