CRUSTACEANS 



are united in the pleon of the female both of that and the remaining species, E. tumefacta. A. Milne- 

 Edwards and Bouvier corroborate these statements in 1 900. Leach adds that in the last-named the 

 pleon has the sixth and seventh segments united as well as the group from the third to the fifth. 

 Pennant's Ebalia is further distinguished from the other two by the cruciform swelling on the 

 carapace, and Cranch's from Montagu's by the more slender elongate 'arms' of the chelipeds. 



The Brachyura anomala or Dromiacea, unlike the genuine Brachyura, have a pair of appendages 

 on the first pleon segment of the female. They make a late and scanty appearance in the Cornish 

 fauna, for though a species of Dromia is figured and described in Leach's celebrated work, Malaco- 

 straca Podophthalmata Britanniae, the figures on Plate XXIV, A, and the description of >. mediter- 

 ranea, Leach, were added in 1875 by Mr. George Brettingham Sowerby, F.L.S., who writes: 

 ' This very hirsute species frequently becomes covered with sponges, so that little of the shell is 

 visible. Although long known as a Mediterranean crab, its existence in our seas has only been 

 recently discovered. The figure is taken from a large specimen now in the British Museum, which 

 was dredged off Penzance, and for some time lived captive in a tank.' Sowerby himself, however, 

 gives a reference to the Zoological Journal (1825), vol. i, p. 419, which shows that John Edward 

 Gray had noted the occurrence of this species on the English coast as early as 1824. The name 

 Dromia mediterranea, Leach, quoted by Gray, was perhaps unaccompanied by any description, 

 otherwise it would have preference over D. vulgarly Milne-Edwards. This western species agrees 

 very nearly with the oriental D. rumphii (Fabricius), but is larger and has the carapace raised into 

 bosses instead of being smooth, besides showing some differences in the lateral teeth. With the red 

 fingers of the chelipeds and the two little hinder pairs of legs laid on the back, this great furry 

 globose species makes an impressive object. It should be noted that in the family Dromiidae the 

 gills are phyllobranchiae, fourteen to sixteen on each side, that the pleon is seven-segmented in both 

 sexes, and that between its sixth and seventh segments there are two little lateral plates, which at 

 least with some probability represent the appendages of the sixth segment that in the genuine 

 Brachyura are always missing. 



The Macrura anomala are subdivided into Paguridea, Galatheidea, and Hippidea. With mem- 

 bers of the first two divisions Cornish waters are rather liberally supplied, and as all our Pagurids 

 have the abdomen or pleon very little calcified and more or less twisted to suit their borrowed habi- 

 tations, they are easily distinguished from the Galatheids, in which the pleon is crustaceous and 

 symmetrical. Both groups are distinguished from the Brachyura by the well-developed appendages 

 of the sixth pleon segment. 



Among the very few notices of Cornish Crustacea which the eighteenth century supplies we 

 have this observation by Borlase : ' Of the shrimp kind, great quantities are taken in Helford 

 Harbour, Mount's Bay, etc. in calm weather. Here we often find the hermit-shrimp, bernard, or 

 eancet/us, remarkable for taking possession of some empty shell, and there fixing his habitation as 

 firmly as if it were his own native place ; when it marches, it draws the shell after it ; in danger 

 retires wholly into it, and guards the mouth with one of its forcipated claws." A footnote says, 

 'Some have erroneously imagined that this was a young lobster I' 1 The knowledge was gradually 

 acquired that ' hermit-shrimps ' are not all of the same species, but the Cornish Paguridae were all 

 in the first instance referred to the one genus Pagurus of J. C. Fabricius, and even in 1878 this 

 arrangement is retained by Spence Bate. They are, however, now distributed among several genera. 

 Professor E. L. Bouvier has supplied the student with a useful clue to the intricacies of the family. 2 

 The genera Eupagurus (Brandt), Spiropagurus (Stimpson), and Anapagurus (Henderson), agree in 

 having the third maxillipeds clearly separated at the base, and the right cheliped generally stronger 

 than the left. But Pagurus (Fabricius), as now restricted, Diogenes (Dana), and Cakinus (Dana), 

 have the third maxillipeds contiguous at the base, and the chelipeds generally subequal, or the left 

 stronger than the right. In the first group Eupagurus has no salient point at the sexual orifices on 

 the basal joint of the male's last thoracic legs, but Spiropagurus has such a process forming a tube long 

 and spirally coiled, while Anapagurus has a simply curved tube, the tube in each case being situated 

 on the basal joint of the left leg. In the second group, although the three genera agree in having no 

 salient sexual appendages, Pagurus alone has horny tips or nails to the chelipeds, and Diogenes alone 

 has a movable process on the ocular segment betwen the ophthalmic scales. In Eupagurus the three 

 Cornish species are thus distinguished by Bouvier. E. cuanensis (W. Thompson) has the upper 

 surface of the right chela very hairy and furnished with numerous sharp tubercles of which the 

 strongest are grouped in longitudinal series, and the inner margin of this chela is straight, the outer 

 much arched. In E. prideaux (Leach) and E. bernhardus (Linn.) the right chela has its upper 

 surface scarcely at all hairy, but furnished with granules or numerous tubercles that are sometimes 

 sharp, and both margins usually a little arched. In E. prideaux the granules or fine denticles are 

 almost all equal, while in E. bernbardus the granules or denticles are rather strong and become 



1 The Nat. Hist. ofCornto. (1758) by William Borlase, A.M., F.R.S., Rector of Sudgran, p. 274. 

 ' La Feuille des Jeunes Naturalistes (1886), ser. iii, 26 Annee, No. 308. 



i 265 34 



