A HISTORY OF CORNWALL 



among stones, beneath which they shelter themselves.' 1 But certainly sometimes fine specimens 

 adventure their dauntless steps within tidemarks, and need to be handled with a little caution. 

 Portunus depurator (Linn.) is called by Bell the Cleanser swimming crab, the specific name in both 

 languages referring to its function as a scavenger. Couch accepts the later title P. plicatus, Risso, 

 alluding apparently to the pleats or sculpturing of the granular but not pubescent surface. He calls 

 it in the vernacular ' Mary crab,' but shows how little distinctive that appellation is by adding, 

 ' There is some difficulty in assigning the proper synonyms to this and the two following species, 

 which are described as inhabiting our coasts, and it is probable that we have one or two more to 

 which none of their descriptions apply. They are all termed Harbour or Mary crabs, and are 

 exceedingly ravenous, fastening eagerly on any animal substance that comes within their reach.' 8 

 The two following species alluded to are P. marmoreus, Leach, the ' Marbled crab,' and P. ko/satus, 

 Fabricius, for which no writer has suggested any English equivalent, but which is called by Costa 

 in Italian, Portuno rasato, the shaven or smooth Portunus. Bell believed that the two names referred 

 to one and the same species, but had not the courage to unite them. Cocks records P. marmoreus 

 from ' Harbour, Carrack roads, trawl refuse, stomach of fishes ; not uncommon ' ; and of P. holsatus, 

 ' One mutilated specimen in the stomach of the M. aeglefinus, 6 December, 1 849.' 3 Mr. Edward 

 Step, F.L.S., has obliged me with excellent specimens from Portscatho. Victor Carus transfers the 

 united species to Stimpson's Liocarcinus, a name signifying 'smooth crab' and a genus in wh ; :h the 

 fourth joint of the third maxillipeds is produced much beyond the front margin of the mouth-cavity. 4 

 It should also be noticed that the distinguished American carcinologist, Miss Mary J. Rathbun, has 

 deprived Portunus of all its English species, supposing herself bound to accept as the type of that 

 genus P. pelagicus, Fabricius, because Latreille in 1 8 1 mentions that particular species and no other. 5 

 But by the same argument P. depurator must be the type, because in 1801 Lamarck names that 

 species and no other, and is quoted as doing so by Latreille himself in 1802. So far, therefore, as 

 the argument founded on Latreille is concerned, our English species of Portunus stand firm. 

 P. corrugatus (Pennant), the ' wrinkled crab,' is mentioned by Couch as scarce. Cocks records it 

 from ' Stomach of fish, Pendower Beach ; not common.' White says, ' the Rev. Alfred Norman 

 has taken it, but rarely, in Cornwall ' 6 It is distinguished from P. depurator by having its front 

 trilobed instead of tridentate and by the much stronger sculpturing of the carapace. P. pusillus, 

 Leach, the ' Dwarf crab,' is much smaller than the rest. Couch marks it common, and Cocks found 

 it at ' Harbour, Bar, Gwyllyn-vase, etc.; not uncommon.' In 1888 Mr. Cornish exhibited to the 

 Penzance Natural History Society ' a specimen of the rather rare dwarf swimming crab (Portunus 

 pusil/us).' 7 Cocks also mentions P. arcuatus, Leach, from ' Harbour, Carrack roads, Bar, Selley's, 

 Olver's, and Glasson's beaches ; common. Two from the stomach of the same fish [Gadus morrhua, 

 the cod previously named], 14 December, 1849,' and P. emarginatus, Leach, from 'Harbour, low- 

 water mark, spring tide ; rare.' 8 These valuable ' Contributions to the Fauna of Falmouth,' to 

 which reference must here be so frequently made, were seemingly quite unknown to Bell in 1853, 

 and to Bate in 1878. They here help to prove that Leach's Portunus with an emarginate front, 

 though rare, is not limited to a single specimen. None the less it may well be, as Leach himself 

 suggests, and as Milne-Edwards and Bell agree in supposing it, specifically identical with the more 

 usual form, P. arcuatus. Leach, in which the front is slightly convex instead of slightly concave. 

 The name emarginatus has technical precedence. Under the other name White says, 'the 

 Rev. Alfred Norman remarks that this species is abundant in Falmouth harbour in 4 fathoms. ' 9 



To the name Portunus /ongipes, Risso, Cocks appends the following observations : ' New to 

 British Fauna, one specimen of this very rare crab was dredged by Professor Forbes, two or three 

 years since, a few miles from Falmouth harbour. The first I found was on the sands, Gwyllyn- 

 vase, after a severe storm in 1845. In 1848 procured two from trawl refuse ; 14 December, 1849, 

 three large specimens from the stomach of the G. morrhua.' 10 Bell in his appendix says : ' The 

 occurrence of this truly Mediterranean species on our southern coast is interesting, as affording 

 another instance of the partial identity of the fauna of the two shores to which I have had occasion 

 so repeatedly to refer. It had not, I believe, been found on our shores until it was dredged on the 

 coast of Cornwall in the year 1 848 by my friends Professor E. Forbes and Mr. McAndrew, from 

 whom I received a male specimen, and subsequently, through the kindness of Mr. Cocks of Plymouth 

 [Falmouth], a female which was taken by that gentleman. I also received a specimen from 

 Mr. R. Q. Couch of Penzance during the year above mentioned. It is doubtless the species 

 described by Mr. Spence Bate as new in the Annals of Natural History for 1851, under the name of 



1 Fauna, p. 71. ' Ibid. p. 72. * Cornto. Soc. (1850), p. 79. 



4 ProJromus Faunae Mediterraneae (1885), i, 517. * Proe. Biol. Soc. Washington (1899) p. 160. 



6 Popular History of British Crustacea (1857), p. 49. 



1 Rep. and Trans, of the Penzance Nat. Hist, and Antij. Soc. (1888-89), P- 9 1 - 

 8 Comw. Soc. (1850), p. 79. 9 Popular History, p. 52. 



10 Cerate. See. (1850), p. 79. 



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