I *08. 147 



anterior third of the carapace ; the lateral spines are slightly 

 posterior to it^ and are continued backwards for a short dis- 

 tance as carinae. The posterior half of the carapace is smooth 

 and rounded, with the exception of a groove which runt< 

 obliquely upwards and backwards behind the lateral carinae. 

 Abdominal somites rather broad, all evenly rounded above; 

 telson somewhat sulcate dorsally. 



Basal joint of antennular peduncle about as long as second 

 and third combined, the subquadrate lateral process reaching 

 somewhat beyond the end of the segment ; second joint con- 

 siderably longer and wider than the third. A.ntennal scale 

 (fig. 2 b) with its outer margin slightly convex, less than two 

 and a quarter times as long as wide, the apical spine falling 

 short of the sharply angled distal end of the lamellar portion. 



Size.—Vp to about 27 mm. 



Colour in life. — The carapace and abdomen are mottled with 

 golden yellow, sienna and umber brown chromatophores ; 

 usually the yellow and sienna are dorsal and the umber lateral. 

 The sienna colouring is sometimes absent and in some 

 specimens the yellow predominates to a very large extent, 

 giving the whole animal a beautiful golden appearance. In 

 other specimens both yellow and sienna are only faintly per- 

 ceptible, the carapace and abdomen being semi-translucent, 

 with umber brown speckling. The eyes are greyish black. 

 The eyestalks, antennules and antennal scales show umber 

 brown or browTi and yellow chromatophores ; the flagella are 

 sometimes marked with red. The distal joints of the outer 

 maxillipedes and first pereiopods are also marked with umber 

 brown and yellow pigment spots , the latter being of large size ; 

 the second and third pereiopods are colourless, while the last 

 two pairs show brown and yellow markings on the merus and 

 carpus and sometimes also on the ischium. The pleopods, 

 telson and uropods follow the general colouring of the abdo- 

 men. 



General distribution. — P. trispinosus is not uncommon in 

 many parts of the North Sea and English Channel and ex- 

 tends south to Gironde (Fischer), the Azores (Barrois) and to 

 Marseilles (Gourret), but is apparently known in the Medi- 

 terranean only from the last locality. It has been recorded 

 from the east coast of Scotland (Scott), from the west coast 

 (Patience, Firth of Clyde) and from the Shetlands (Norman), 

 but is not known on the Scandinavian shores. 



Irish distribution. — First taken in Irish waters off Skerries, 

 Co. Dublin. During the course of fishery investigations P. 

 trispinosus has been found very frequently near the Kish and 

 Burford Banks, off the mouth of Dublin Bay, in 10-12 fathoms 



1 By this character P. trispinosus is very readily distinguished from 

 young Crangon vulgaris; to which it bears a superficial resemblance. 



K 2 



