on the British Shores. 231 



grooved ; anterior extremities large, armed with five pointed 

 spines disposed in a line ; the abdominal segments furnished, 

 on each side, with two elevated longitudinal ridges above the 

 recurved marginal edge, which appears like a third ridge, 

 on each side ; the last segment but one has four such ridges 

 on each side the centre ; the caudal segment is carinated in 

 the middle, the keel ending in a point above the surface, the 

 posterior edge divided by six strong projecting points, three 

 on each side, with denticulated intervening spaces ; attached 

 to the under surface of this portion are lateral articulated 

 processes, flattened, oval, and ciliated. 



The species of ^quilla are remarkable for their form, par- 

 ticularly for the comb-like appearance of the extremities of 

 the first pair of limbs ; and, according to M. Risso the pre- 

 sent species is subject to some variation in colour. They live 

 principally in deep water ; but the females resort to the rocks 

 in March and August, to deposit their ova, which are of a 

 yellow brown colour. The present species, named by M. 

 Risso after M. Desmarest, is more plentiful in the Mediter- 

 ranean than Squilla Mantis. 



Their external covering, though thin, is firm; and their 

 mode of swimming and general progression is similar to that 

 of the lobster. In their nature they are timid, and endea- 

 vour to escape whenever they are pursued. Their flesh is 

 said to be very good, and is eaten almost daily. 



Of the several fishes lately added to our British catalogue, 

 four are well-known Mediterranean species. The Squilla 

 here noticed is also common to the same sea ; and from the 

 last published part of the Linncean Transactions I make the 

 following extract, which still further illustrates the subject 

 with which I had intended to conclude this notice : — " Mr. 

 Dillwyn, F.L.S., exhibited a series of specimens of the Ian- 

 thina fragilis of Lamarck, the Helix lanthina of Linnaeus, 

 collected from Oxwich Bay, to the west of Swansea, accom- 

 panied by a letter stating that the same shell, which is abun- 

 dant in the Mediterranean, had been found once before there 

 in some abundance. Mr. Dillwyn considered the recording 

 such facts of importance, as being likely to throw some light 

 on the under-currents of the ocean." {Linn. Trayis. vol. xvi. 

 p. 751.) Dr. Grant found specimens of the same shell, with 

 the animals alive, on the coast of Cornwall, in the month of 

 September last. 



Considerable additions to the catalogue of British Crustacea 

 have recently been made, several of which have been recorded ; 

 but I am not aware that any notice of the occurrence of a 

 species of true Squilla has been published hitherto. 



Q 4 



