CRUSTACEANS 



alone differing by having only three teeth and a tubercle on the front 

 half of its long side margin and a little tooth close to the hinder ex- 

 tremity of it. 



The section Catometopa, or crabs with a downward bent front, to 

 judge by existing records, has only two representatives in Sussex. Of 

 these Goneplax angulata (Pennant) is marked rare in the Natural History 

 of Hastings} This species resembles Corystes cassivelautnis in the great 

 length of its chelipeds, but its second antenn;r are short and its carapace 

 is broader than long. Its name by interpretation is a plaque or tablet 

 with angular corners. The hind corners however of the carapace are 

 rounded, but the front ones, against which the long eye-stalks fold down, 

 are exceedingly sharp. The family Goneplacids is spoken of as showing 

 a close resemblance to the Cyclometopa, being an instance of those 

 transitions which make classification difficult and the study of nature 

 interesting. Among the Pinnotherida?, Pinnotheres pisum (Linn.), which, 

 in contrast to the preceding species, is a little short-armed, round button 

 of a crab, is noted by the Natural History of Hastings as common,^ and 

 this may very well be, since its well known habit of taking lodgings with 

 a mussel, an oyster, or some other obliging mollusc, gives it a kind of 

 freedom to be found in all waters where its hosts foregather. 



With species of the section Oxyrrhyncha the county is fairly well 

 supplied. In these the front is usually more or less sharply produced, 

 and ' the beak ' is often divided into two acute horns. 



The family Inachids contains seven of the species here requiring 

 notice. Macropodia rostrata (Linn.) was obtained from Sussex by Bell, 

 who calls it Stenorynchus phalangium (Pennant), although by his own 

 confession these are not its earliest names. He quotes from Mr. Hailstone 

 the statement that ' it is very common at Hastings, both among the rocks 

 on the shore, and in deep water, and is occasionally caught in the trawl- 

 net in vast numbers : of sixty-eight specimens brought up at once 

 the proportion of males to females was as two to one.' ^ Macropodia 

 tenuirostris (Leach) was taken by Bell in prawn pots at Bognor. He 

 says, ' this elegant species may be readily distinguished from the former 

 by the long attenuated rostrum, by the existence of a small spine on the 

 epistome immediately behind the basal joint of the external antennse, and 

 by a series of minute spines on the inner part of the arm : the body is 

 altogether more elongated, and the spines more acute, but in other 

 respects the characters are nearly the same.' * For comprehending these 

 distinctions it is necessary to remember that the so-called ' arm ' of the 

 chelipeds is the long joint which immediately precedes the three ter- 

 minal joints called wrist, hand and finger. The fixed thumb of the hand 

 and the movable finger form the chela or nippers of a crustacean. The 

 epistome or over-mouth is to be found on the under side of the crab, 

 just above that important 'buccal area' which is more or less closed 

 in by the external maxillipeds. The species M. tenuirostris was long 

 identified with Inachus longirostris, Fabricius, but Miss M. J. Rathbun 



1 Nat. Hist. Hastings, p. 41. '^ P- 4i- ^ P- +■ ^ p. 6. 



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