T H A 



275 



T H A 



bent (coudees), as in Pagurus ; the third joint of thei: 

 peduncle the longest, and carrying at its extremity two 

 small multiarticulate appendages, which are very short ant 

 rather stout, one of which is furnished with many lorn, 

 hairs. External antenna; inserted lower than the pre" 

 ceding, their peduncle bent, and presenting above a smal 

 scale, the vestige of a palp. External jaw-feet peditbrm 

 The last thoracic ring not anchylosed to the preceding. 

 Anterior feet terminated by a "stout, didactylous, well- 

 formed hand : they are of very different sizes. Second anc 

 third pairs slender and very long : the two last pairs, on 

 the contrary, short and elevated against the sides of the 

 body, as in the Paguri ; the fourth pair are flattened 

 rather large, and imperfectly didactylous, the immoveable 

 finger of their hand being only formed by a slightly pro- 

 jecting tubercle ; the posterior feet, still smaller than the 

 last, nre terminated by a small didactylous rather well- 

 formed hand. The abdomen is narrow, elongated, and 

 perfectly symmetrical : the first ring, much narrower than 

 the succeeding ones, has no appendages ; the four nexl 

 segments, on the contrary, each give attachment to one 

 pair of rather large false natatory feet, formed by a cylin- 

 drical basilary joint and two terminal blades, one of which 

 is very small and obtuse, and the other large, pointed at 

 the end, and bordered with long ciliary hairs, ('mula/ /in 

 moderate in size ; the middle blade, formed by the seventh 

 abdominal segment, is rounded and ciliated, and the ex- 

 ternal blades are much longer than the middle ones. 

 (M.B.) 



M. Milne Edwards observes that this sfenus establishes 

 the passage between the Pagurians and C<I//-/HI/U*X<I. 



K\;imple, Glducothoe Peronii, the only species known. 

 Its integuments have little solidity, its carapace is smooth, 

 and its length 8 lines. M. Milne Edwards states that it 

 appears to inhabit the seas of Asia. He is of opinion that 

 Latreille's genus Prophylax approximates closely to 

 tikoa, :ind ought not perhaps to be distinguished 

 from it : if so Latreille's name has the priority. The latter 

 placed his genus among the Pasuri, but after the publi- 

 cation of M. Milne Edwards' s (Jtaucothoe, was uncertain, 

 according to M. Edwards, whether these two generic di- 

 visions should not be united. 



CMianassa. (Leach.) 



See the article : but the student should refer to the accu- 

 rate and elaborate description and figures of M. Milne Ed- 

 wards, who records two species. : CouiaRotta s-ubterranea 



Axia SCirhymhui; 

 , Intermediate intenna ; I, external antenna. 



and uncinata ; and he adds that Callianassa major of Say 

 seems to be distinguished from the two preceding species. 



Axia. (Leach.) 



Generic Character. Carapace very much compressed, 

 and terminated anteriorly by a small triangular rostrum. 

 Ocular peduncles very small, cylindrical, and terminated 

 by a hemispherical cornea. Terminal filaments of the 

 internal antennce nearly of the length of the carapace. 

 Peduncle of the external antenna; having above a small 

 moveable spine which represents the great lamellar palp 

 observable in the Shrimps. External jaw-feet slender and 

 peditbrm. Anterior feet compressed, and terminated by a 

 well-formed claw ; carpus small. Second pair of feet nearly 

 lamellar, and equally didactylous. The three next pairs 

 monodactylous. Abdomen slightly convex towards the 

 middle, and terminating in a great fin, the five blades of 

 which are nearly of the same length. First ring of the 

 abdomen carrying a rudimentary pair of false feet, and the 

 four succeeding rings provided each with a pair of very 

 well-developed natatory false feet, each composed of a 

 short and stout peduncle, which at its extremity carries 

 a small styliform appendage within, and externally two 

 great oval, very large blades, which are ciliated on the 

 borders. (M. E.) 



M. Milne Edwards observes that this genus much re- 

 sembles Callianassa and Gebia, and he records the only 

 known species, Axia Stirhynchus. Its length is about 

 three inches, and it inhabits the coasts of France and Eng- 

 land. 



Gebia. (Gebios and Thalassina, Risso ; Gebia and 



Upogebia, Leach.) 



<li iit-rif Character. Carapace terminating anteriorly 

 by a triangular rostrum, and sufficiently large to cover the 

 eyes almost entirely ; on each side of its base is a tooth, 

 which is continued with a crest, and forms the lateral 

 border of the upper surface of the stomachal region. In- 

 ternal antennce very short, but nevertheless their terminal 

 filaments are longer than their peduncle. External an- 

 tennce very slender, and presenting at their base no vestige 

 of a moveable scale. External jau- -feet pediform. Anterior 

 feet narrow, terminated by an elongated and imperfectly 

 subcheliform hand : their moveable finger is very large, 

 and in bending downwards its base is applied against the 

 anterior border of the hand, the lower angle of which is 

 prolonged so as to constitute a tooth performing the office 

 of the immoveable finger. The feet next in succession are 

 compressed and monodactyle ; the second pair have their 

 penultimate joint large, widened, and ciliated below ; the 

 succeeding pairs are more slender. Abdomen long and 

 much narrower at its base than towards its middle, de- 

 pressed and terminating by a large fin, whose four lateral 

 :>Iades are foliaceous and very wide. First abdominal ring 

 with two pairs of very small filiform appendages ; the four 

 next segments giving origin to three pail's of false natatory 

 feet, composed of a stout and short peduncle, and two oval 

 Blades with strongly ciliated borders : the external one very 

 arsje. and the other very small. Branchicc brush-like and 

 ixed on two rows, namely, one above the second foot, and 

 .wo above the four anterior feet and the external jaw-feet. 

 M.E.) 



Example, Gebia stellata. Length 1 inch. 



Locality. Coasts of England. M. Milne Edwards states 

 hat this species comes very near to Gebia littoralis. 



M. Milne Edwards observes that the Gebice establish the 

 jassage between the Thalassince and the Axia?, which last 

 hey resemble in the general form of the body and disposi- 

 tion of the caudal fin, whilst they approach the first by the 

 conformation of the feet. 



X^^ 



Ocbia siclliita. 



a, intermediate antenna ; 4, base or nn extern*] antenna. 



2N2 



