C II U S T A C E O L O G Y. 



401 



MiVdceiiS. 



Urttstacea. Sp. Q.Flavescens. Body entirely yellow. 

 Alphceus flavescens of Latreille. 



Sp. 3. Marmoratus. Body pale rufous, mottled with 

 armora- red. 



Alphceus marmoratm of Latreille. 

 This and the foregoing species inhabit the East In- 

 dian ocean, and are described by Latreille, from speci- 

 mens in the French museum of natural history, and on 

 his authority we introduce them here. 

 Pen - Genus XLVI. Pen^eus. The exterior lower than 



the internal antennae, with a scale attached to the pe- 

 duncle, (often notched on the external side of the apex). 

 The six anterior feet compound ; the anterior pair short- 

 est. Middle process of the tail-fin oblong-triangular, 

 the apex much narrower than the base. 

 nodon. gp. i > Monodon. Rostrum porrected, and turning 

 upwards ; serrated above, armed with three teeth be- 

 low. 



Pendens monodon of Fabricius and Latreille. 



Observe. To this section another genus (not hitherto 

 defined by any author) seems to belong, which contains 

 Cancer astacus gibbosus of Montagu. Lin. Trans, vol. ix. 

 pi. 5. fig. 1 . But as we have never seen perfect speci- 

 mens, we refrain from attempting a generic character, 

 which must necessarily be very defective. We shall 

 therefore describe the animal in Montagu's own words. 



" Body slender, incurvated, with six joints. Thorax 

 smooth. Proboscis long, laterally compressed, and ser- 

 rated ; a small spine on each side the proboscis, and 

 another beneath each eye. Antennas four ; upper pair 

 shortest and bifid ; lower pair single, nearly as long as 

 the body. Two anterior ciliated plates. Eyes pedun- 

 culated. Arms and legs scarcely definable ; the ante- 

 rior pair is terminated by a quadrifid joint ; the second 

 pair is cheliform, the other three pair appear when 

 magnified to have a toothed claw. Besides these, there 

 are two very long and slender appendages, which do 

 not strictly appear to be legs, but seem to be auxiliary 

 to the palpi, though they originate so far from the 

 mouth, for they are always placed forwards towards the 

 mouth ; these are slightly chelate. The caudal fins are 

 similar to those of the prawn, with a slight spine near 

 the end of the exterior pair. Colour, when alive, red. 

 Length about an inch. Not unfrequently taken by 

 dredging at Torcross, Devonshire." See Hippolyte in 

 the Index. 



** Interior antennae with three setae. 

 Puje- Genus XLVII. Paljemon. Four anterior feet com- 

 ". pound. ' 



A. Anterior pair smaller than the second. 

 Ha. Sp. 1. Squiila. The rostrum acute, and turning up- 



wards ; the superior part with seven teeth, longer than 

 the peduncle of the internal antennae. 



Cancer squiila of Linne. Astacus serratus of Pen- 

 nant. Palamon squiila of Fabricius and Latreille. 



Inhabits the European ocean, frequenting most of our 

 shores, lurking amongst loose stones and alga?, in pools 

 left by the tide, where it is taken by means of a small 

 Ret fixed to a hoop. It is the common prawn of our 

 markets. When alive, cinereous, elegantly banded with 

 brown ; but by boiling, it acquires a fine red colour. 

 Pennant says, that it is frequently taken over thirty fa- 

 thoms depth of water, but we have never observed it 

 in such a situation. Length five inches. 

 ians. Sp. 2. Varians. Rostrum straight, a little longer 



than the peduncle of the middle antenna?, with four 

 teeth in the upper side. 



Pa/a:mon varians, Leach's MSS. 



V©1>, V5I. PART I*. 



A very common species on the Devonshire and Gla- Crustacea, 

 morgan coasts, where it is taken and sold under the S —V"""'' 

 name of shrimp. It may possibly be Astacus squiila of 

 Pennant, but the descriptions of that author are so la- 

 conic, that we are in great doubt in this as in various 

 other instances. Length two inches and a half or three 

 inches. 



B. Anterior larger than the second pair of legs. 

 Sp. 3. Nitescens. Rostrum without teeth. Nitesccu!, 



Cancer astacus nitescens of Montagu. Athanas nites- 

 cens, Leach's MSS. 



Found on the southern coast of Devonshire by Col. 

 Montagu. Length one inch, or rather less. 



Division II. Hands without the finger, having only 

 a moveable thumb. 



Genus XLVIII. Crangon. Anterior pair of feet 48. Cram. 

 largest, and furnished with a moveable thumb; the GD *" 

 other four pair unequal and simple. 



Sp. 1. Vulgaris. Shell smooth, rostrum short, with Vulgaris, 

 a single groove above. See Plate CCXXI. Fig. 5. Pr ATE 



Cancer crangon of Linne. Arfaci/s crangon of Pen- CCXXJ 

 nant. Crangon vulgaris of Fabricius and Latreille. Fig. 5. 



Inhabits all the sandy shores of the European ocean; 

 is the common shrimp of the English markets. Its co- 

 lour when alive is cinereous, inclining to transparent, 

 beautifully mottled and spotted with brown and black- 

 ish-brown. 



Division III. All the feet simple, having neither 

 finger or thumb. 



Genus XLIX. Praunus. Legs on each side four- 49. 1»ai». 

 teen, set in a double series at the sides of the thorax, n-js. 

 Female furnished with a pouch, situated at the base of 

 the abdomen, in which she carries her young after their 

 exclusion from the ear"-. 



This genus was instituted by Mr Leach, who has de- 

 rived the name from the English word prawn. 



Sp.l. Flexnosus. Middle process of the tail-fin deep- Flexacwts 

 ly notched. 



Cancer Jlexaosus of Miiller. Cancer multipes of Mon- 

 tagu. Lin. Trans, vol. ix. tab. 5. fig. 3. Praunus Jlexu- 

 osus, Leach's MSS. 



■ Discovered as an inhabitant of Britain by Mr Henry 

 Boys of Sandwich. It has since been observed by Mr 

 Montagu on the south coast of Devon, and accurately 

 described by him in the ninth vol. of the Linnean Trans- 

 actions. As he never saw it alive, the following ac- 

 count, extracted from Mr Leach's MSS. may not prove 

 uninteresting, 



** Colour when alive pellucid-cinereous. Eyes black, 

 red at their base. Laminae of the head with a black 

 longitudinal lme, and spots. A clouded spot on each 

 side the hinder part of the thorax, and another above 

 the legs. Every segment of the body above beautiful- 

 ly marked with a reddish rust-coloured spot, disposed . 

 in an arborescent form ; tail-fin spotted with the same 

 colour, mixed with black. Pouch of the female with 

 two rows of fuscous-black spots. Under side of the ab- 

 domen regularly mottled with rufous-black. It is found 

 with fry from the middle of June to the middle of Ju- 

 ly. Females one-third more abundant than the male-." 

 Mr Leach observed them in great abundance in pools 

 left by the tide in the Frith of Forth near Lcith. Len^tl 



gtn 



an inch and a quarter." 



Sp. 2. Integer. Middle process of the tail entire and 

 not notched. 



Praunus integer, Leach's MSS. 



This species was discovered by Mr Leach at Loch- 

 Rgnza, Isle of Arran, in brackish pools left by the tide, 



* E 



lme 



