PINNOTHERES, OR PEA-CRABS. 89 



and suffocates whatever it incloses, giving a share of the booty 

 to her companion." — Pliny, Hist. Nat. Lib. IX. cap. xlii. 

 This history is nearly copied after Cicero de Nat. Deorum, 

 Lib. II. cap. xlviii. Oppian has a conceit still more absurd, 

 giving to the Pinnotheres a remarkable degree of ingenuity 

 and dexterity, in supposing that it throws a small stone between 

 the valves of bivalve shells, on finding them open, which pre- 

 venting them from closing, enables it to devour the inhabitant! 

 Hasselquist goes astray in another direction, and supposes the 

 crab to go out and cater for the Pinna, and when it returns, 

 to cry out for the shell to be opened ! ! 



On a due consideration of the facts stated in the former part 

 of this memoir, and reasoning from analogy, we may fairly 

 conclude that the crab is altogether useless and quite unneces- 

 sary to the well-being of the shell-fish, and indeed attended 

 with more or less inconvenience and annoyance, but that the 

 shell-fish is absolutely requisite to the very existence of the 

 crab, as much so, as all other animals to their respective 

 parasites. 



The species of this genus would merit a separate memoir, 

 bearing in mind the discrepancies presented by their young and 

 by the two sexes, which even misled the best Crustaceologist 

 of the age, who mistook both the one and the other for so 

 many different species, describing the young as Pinnotheres 

 Latreillei, and the male as P. varians. — Mai. Pod. Brit. 

 T. XIV. f. 9, 10, 11. 



On this part of the Irish coast but two species have been 

 hitherto observed, viz. P.pisum and P. pinnce, the latter being 

 found in Pinna and Modioli. In the Mediterranean and Red 

 Sea, some others are met with in the various species of Pinnce, 

 and as some of these are %\ feet in length, we find their para- 

 sitic Pinnotheres to harmonize in relative size, being in these 

 huge bivalves nearly as large as a pigeon's egg. In America, 

 one species inhabits the Ostrea virginica. In the West 

 Indies one has been discovered by the late L. Guilding, in a 

 cell, near to the muscular attachment of the animal of Turbo 

 pica! Many more will, no doubt, be added to the list of 

 species already known, now that the attention of Naturalists 

 has been directed to these singular animals. 



From the statements of Aristotle and Pliny before alluded 

 to, and those of a later date, by Forskal, Desc. Anim. p. 94, 

 under the head of Cancer custos, of which he gives as the 



no. r. VOL. III. N 



