432 



CRUSTACEOLOGY. 



Appendix, palpi, with three exserrted joints, the last spiniferous; 

 S **"'"Y""™"' four anterior feet, didactyle, the anterior pair shortest 

 and thickest ; nails of other feet spinous ; third joint of 

 abdomen gibbous above. 



Observe. To this gi nus Cancer astacus gibbosus of 

 Montagu, already referred to in the note after Penaeus, 

 page 401, belongs. 



Sp. 1. Varians. Rostrum strait, with two teeth above 

 and beneath; shell abcnge and beneath the eyes with a 

 spine. 



Inhabits the rocky shores of Devon in great plenty. 



Hippolyte varians ; Leach, Mem. Wern. Soc. vol. ii. 



There are other species which are not well understood. 



Gen. Pandalus. Superior antennae with two setae, 

 the inferior ones with a squama at their base. First 

 pair of feet simple, the second pair didactyle ; nails of 

 the other feet spinulose ; third segment of the abdo- 

 men gibbous above ; pediform palpi, with three exsert- 

 ed joints, the last acuminate and spinigerous. 



Sp. 1. Montagui. Rostrum turning upwards, with 

 many teeth above, and the apex emarginate, with six teeth 

 beneath; antennae ringed with white and red alternately. 



Pandalus Montagui, Leach, Malacos. Brit. Panda- 

 lus, Tab. A. named in honour of the first discoverer, 

 Montagu, by whom it was called Astacus macnlalus. The 

 Rev. J. Fleming took this species in Zetland, whose 

 successful labours in that country speak more tha*: we 

 can do in words. 



Gen. Palcemon. Page 401. A. Anterior pair of 

 feet smaller than the second ; pediform palpi, with the 

 last simple and acuminate, shorter than the preceding 

 joint ; superior antennae with three setae. 



Observe. We can correct an error in nomenclature, 

 which we have lately discovered. 



Sp. 1. Serratus. Rostrum ascending, above with 

 from six to eight teeth, and the apex notched ; beneath 

 with from four to six teeth. 



Astacus serratus of Pennant. Palcemon squilla of La- 

 treille; and this article, page 401. Palcemon serratus of 

 Fabricius, seems referable to a distinct genus, from his 

 description, if it be correct. 



Sp. 2. Squilla. Rostrum strait, with from seven to 

 eight teeth above, and two to three beneath. 

 - Cancer squilla, of Linne. 



Is very common on the Devonshire coast ; has the 

 same colour as P. serratus, but spawns at a different 

 season. A little shorter than the preceding species. 



Sp. 3. Varians. The rostrum strait, with from four 

 to six teeth above and three beneath. 



Is common at Yarmouth, and is frequently also taken 

 on the Devon and Glamorgan coasts. 



Gen. Athanas. Palcemon. Page 401. B. Anterior 

 larger than the second pair of feet ; pediform palpi, with 

 joint simple and acuminate longer than the preceding; 

 •superior antennae with three setae. 



Sp. 1. Nitescens. Palcemon nitescens. Page 401. 



ORDER III. GASTERURI. 

 Tribe I. GNATHIDES. 

 This includes our former family, Gnathonii. 

 Tribe II. GAMMERIDES. 



This tribe includes our family Gammarini, which is 

 mow divided into several families. The last character, viz. 

 " tail not distinct from the body," should be cancelled. 

 Family 1. Orchestid^e. 



Antennae four jointed, the last joint composed sever- 

 al minute joints ; the upper ones very short, shorter 

 than the peduncle of the under ones. 



Genus I. Talitrus. Page 402. Appenriir, 



Sp. 1. Locusta. Dr Leach has discovered T. liltoralis s - "T" w ' 

 to be merely the other sex of this species. 



Genus II. Orchestia. Page 402. Four anterior 

 feet of the male monodactyle, the second pair largest ; 

 of the female equal in size, the first pair monodactyle, 

 the second didactyle. 



Family II. Dexamerid.e. 



Antennae three-jointed, the last joint composed of 

 several other minute articulations ; upper ones longest. 

 * Two anterior pair of feet monodactyle. 



Genus III. Dexamine. Four anterior feet nearly- 

 equal ; hands subovate, compressed, and filiform. 



Sp. 1 . Spinosa. Cancer gammarus spinosus of Montagu. 



** Anterior pair of feet didactyle ; second pair mono- 

 dactyle. 



Genus IV. Leucotiioe. Thumb of anterior feet 

 with two joints ; second pair with a compressed hand ? 

 furnished with a curved thumb. 



Sp. 1. Articulosa. Page 403. 



Family III. Gammarid;e. 



Last joint of the antennae composed of several mi- 

 nute articulations ; upper pair longest, four jointed ; 

 under ones five-jointed. 



* Second pair of feet larger than tJiefrst, with a com- 

 pressed hand. 



Genus V. Melita. Second pair of feet (in the male 

 at least) with the thumb bending upon the palm ; last 

 joint of the antennae entire. 



Sp. 1. Melita palmeta. Page 403. 



Genus VI. Mjera. Second pair of feet with a large 

 compressed hand and single thumb ; last joint of the 

 antennae bifid. 



Sp. I. Grosnmana. Page 403. 



** Four anterior feet nearly equal in size and form, 

 with ovate hands. 



Genus VII. Gammarus. Last joint but one of the 

 superior antennae with a litle seta at the apex at the 

 base of the articulated last joint ; back of the tail with 

 ciliae of spines. 



Contains Gammarus pulex, locusta, and camylosps of 

 this article, page 402 and 403. 



Genus VIII. Ampithoe. Superior antennae, with- 

 out a seta at the base of the last joint ; back of the tail 

 without fasciculi of spinules. - 



Sp. 1. Rubricata. Gammarus rubricalus. Page 403. 

 *** Four anterior feet with a filiform hand. 



Genus IX. Pherusa. 



Sp.l. Fucicola. Colour whitish, nuttled with reddish. 



Found on the rocky shores of Devon, under stones 

 at low tide, on fuci. 



Family IV. PodoceridjE. 



Superior antennae shortest four-jointed, the last joint 

 solid or obscurely articulated; inferior antennae five- 

 jointed, with the last joint solid, or very obscurely ar- 

 ticulated. 



* Superior antennae very short, the last joint composed 

 of many minute articulations. 



Genus X. Corophrium. Body elongate, ten-joint- 

 ed ; tail three-jointed, the first joint and the second with 

 a bifid style ; the last with two moveable papillae ; an- 

 terior pair of feet small, with the apex somewhat trun- 

 cate, and furnished with a little thumb; second pah- 

 larger, armed with a thin curved thumb. 



Dr Leach formerly considered this genus as consti- 

 tuting a peculiar family, which, with the addition of 

 two other genera, he has now completely established as 

 such. For the species, see page 403. 



