CRUSTACEANS 



study these little crabs with their legs folded up look more like small rudely-chipped bits of stone 

 than animals high in the scale of organic life. 



Passing fi-om the true crabs to the ' hermits,' which are only crabs by courtesy, we have 

 among the Macrura anomala, in the family Paguridae, the familiar Eupagurus bernhardus (Linn.). 

 Mr. Morley reports this as represented in the Ipswich Museum, and adds his own opinion that it 

 is 'doubtless abundant.' From the same division Metzger reports, in the family Galatheidae the 

 species Galathea squamifera. Leach, and G. intermedia, Lilljeborg, both taken south-east of Yarmouth 

 at the depth of 23 fathoms. From the ' hermits ' these little lobster-like animals are distinguished 

 by having the pleon symmetrical. Between the two species here named there is a distinction not 

 immediately obvious. A little examination will show that the appendages of crustaceans are 

 sometimes branched and sometimes simple. It is not uncommon for the first joint to carry an 

 accessory branch known as the epipod, and for the next joint to have a branch called the exopod. 

 The Brachyura and Macrura agree in having five conspicuous pairs of limbs, spoken of as legs, 

 or technically as peraeopods, though the diversity of functions they fulfil sometimes makes any 

 common name for them rather inappropriate. Often the first pair are grasping organs, or 

 chelipeds. Now, in Leach's ' scaly Galathea ' the chelipeds and two following pairs of legs carry 

 epipods, which in G. intermedia are confined to the chelipeds. To explain the name of the 

 ' intermediate Galathea ' we must notice a third species, G. strigosa (Linn.), in which none of these 

 limbs have epipods. Thus Lilljeborg's species stands between a species with three pairs and a 

 species without any. It would be interesting if some of our experimentalists could ascertain 

 whether these differences are co-ordinated with any differences in the habitual life of the crea- 

 tures, and whether the simplification of structure should be regarded as an advance or an inferiority. 



The genuine Macrura have a familiar representative on the coast of Suffolk in the common 

 lobster, Astacus gammarus (Linn.), of the family Nephropsidae. The neighbouring family Pota- 

 mobiidae supplies the river crayfish, Potamobius pallipes (Lereboullet). According to Mr. Claude 

 Morley, the Ipswich Museum has a specimen of it, taken from the River Gipping at Stow- 

 market. Mr. Cooper, sadler at Kirkby, Lowestoft, assured us that in his schooldays crayfishes were 

 common in the River Waveney, near Yarmouth. The crayfish eats animal food, but combines 

 with this a vegetable diet. Especially it is said to be fond of the Characeae or stone-worts which 

 abound in the East Anglian Broads. The lime with which these plants incrust their delicate stems 

 and leaves supplies what is needed for hardening the chitinous skeleton of the crustacean. 



The tribe Caridea, embracing so many of the species popularly known as shrimps, is moderately 

 well represented on this coast. In the family Crangonidae Crangon vulgaris, Fabricius, the common 

 shrimp, justifies to some extent its specific name and English epithet, although there is another 

 species also commercially prominent in this part of the world. In the same family Metzger reports 

 Crangon trispinosus. Hailstone, and C. nanus, Kroyer, both from 22 fathoms, south-east of Yar- 

 mouth.^ From the same locality he records in the family Hippolytidae Hippolyte pusiola, Krfiyer, 

 at 23 fathoms,' and Firbius fasciger, Gosse, at 16 fathoms, and in the Pandalidae Panda/us brevi- 

 rostris (Rathke), at 23 fathoms.* To this group must be added Pandalus montagui. Leach, and in the 

 Palaemonidae Palaemonetes varians (Leach). Some of these species, however, in the progress of 

 science during the last hundred years, have undergone various changes of nomenclature, owing to 

 successive discoveries as to their structure and true systematic position. The first family is dis- 

 tinguished from the others by the subchelate character of the first legs. They are not fully formed 

 chelipeds. The sixth joint, or hand, is not produced into a thumb opposable longitudinally to the 

 seventh joint or finger. The clasping effect is produced by the widened distal margin of the hand, 

 across which the finger closes more or less obliquely. In the families Hippolytidae and Pandalidae 

 the second legs have the fifth joint, or so-called wrist, divided into several secondary articulations, 

 which is not the case in the Crangonidae or Palaemonidae. But whereas the Hippolytidae have 

 the first legs clearly didactyle, in the Pandalidae these limbs are either simple or only microscopically 

 chelate. The species cited by Metzger as Crangon trispinosus was placed by Kinahan in a new 

 genus, Cheraphitus, to which also C. nanus was referred by Sars. The name Cheraphilus, being 

 open to objection, has since been changed to Philocheras^ and, Kroyer's species having been identified 

 with Westwood's earlier Crangon bispinasus, the name should now be written Philocheras bispinosus 

 (Westwood). In the genus Crangon the second pair of legs are subequal in length to the rest, but 

 they are much shorter than the rest in Philocheras. Recently Dr. Caiman has recalled attention to 

 the fact that in Crangon vulgaris there are six pairs of branchiae, the arthrobranchia of the third 

 maxilliped having sometimes been overlooked, which, he says, ' although small, is not at all difficult 

 to see.'* He refers to Huxley's recognition of this feature given in the Proceedings of the Zoological 

 Society for 1878,' but does not notice the misleading contradiction which has there slipped into 



* Loc. cit. 291. ' Ibid. 286. • Ibid. 289. 



' South African Crustacea (1900), pt. i, p. 48. 



' National Antarctic Expedition, Nat. Hist. (1907), ii, 6, 'Crustacea.' 'Op. cit. 783. 



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