CRUSTACEANS 



left naked, but clothed again by the crustacean's industrious fingers. So long ago as 1865 Mr. Spence 

 Bate remarks, ' In Pisa this is no accidental occurrence, since all the spines are sharp-pointed and 

 curved, and my friend Mr. Whitford has informed me that he has observed specimens in his aquarium 

 which, soon after having cast their exuviae, pick up with their claws pieces of weed and place them 

 on the spine.' 1 So in 1900, A. Milne-Edwards and E. L. Bouvier carefully stripped specimens of 

 their new species Achaeus cursor, and saw them skilfully put pieces of bryozoa and corallines on their 

 legs and carapace till those parts gradually disappeared from view. 8 



The Cornish genera of this tribe are distributed over three families : Inachidae, Hyadidae, and 

 Mamaiidae. In the first the eyes are without orbits ; in the second with imperfect orbits, which 

 cannot conceal the cornea ; in the third they are with or without orbits, but have in any case pro- 

 tecting processes, and in the English species can entirely conceal the fully retracted cornea from 

 dorsal view. 3 



Of the Inachidae, Cornwall has six species. Macropodia rostrata (Linn.), ' The long-legged 

 spider crab,' often called Stenorrhynchus (or Stenorynchus) phalangium, was not known as Cornish to 

 Couch in 1838, but Cocks reports it from 'Harbour, trawl refuse, crevices of rocks and under sea- 

 weeds, low-water mark ; Gwyllyn-vase, Swanpool, etc., not uncommon' ; and Bell says that he has 

 ined it from the coast of Cornwall. 4 Macropodia tenuirostris, Leach, distinguished from the pre- 

 ceding by its much more elongated rostrum, was found by Leach to be a very common inhabitant 

 of all the deep water off the south-west coast, ' especially in the Sound of Plymouth.' 5 Couch, who 

 calls it the ' Smaller sea-spider,' and uses for it the specific name longirosiris (now shown to be a 

 synonym of the above-mentioned rostrata), says that it is ' common at the depth of from two to 

 twenty fathoms, and often taken in crab-pots.' 6 The little Achaeus cranchii, Leach, ' Cranch's 

 spider-crab,' is peculiarly a child of the county, having been first discovered by Mr. John Cranch in 

 dredging off Falmouth. 7 Twenty-three years later Couch speaks of it as 'a rare species, the only 

 British recorded specimen having been taken at Falmouth. 8 Cocks in 1850 reports it from 

 ' Gwyllyn-vase, south ; extreme low water mark, spring tide, on Sertularia pumila ; very 

 rare, only three recorded specimens.' Achaeus is distinguished from the preceding genus by 

 the form of the rostrum, which consists of two short lobes instead of two long spines, but 

 shares with it the peculiarity that the eyes are not retractile, whereas in Inachus they can be 

 in a measure retracted by being laid back against the carapace. All the three genera 

 have the pleon six-segmented in both sexes through coalescence of the last two segments. 

 Inachus dorsettensis (Pennant) is recorded by Couch as, 'commonly taken in crab-pots within a 

 few miles of the shore at all depths.' 9 He calls it the ' Scorpion sea-spider,' with reference 

 to the specific name used by J. C. Fabricius. Cocks reports it from ' Harbour, Carrack Roads, 

 trawl refuse : low-water mark, Gwyllyn-vase ; common.' I. dorynchus, Leach, according to Couch, 

 who calls it the ' Feeble Inachus,' is not uncommonly found on board crab-boats. 10 It is reported by 

 Cocks from ' Harbour, Carrack Roads, trawl refuse ; common, under stones. Gwyllyn-vase ; not 

 uncommon.' In the cardiac region, that is the hinder, but not quite the hindmost part of the 

 carapace in the median line, this species has three small tubercles where the ' Scorpion ' has one 

 that is large and spiniform, and there are several other similar distinctions, which, however, the 

 student will not find easy to observe until he has carefully undressed his specimens. From both of 

 the foregoing species /. leptochirus y Leach, is separated by superior size, more slender chelipeds, and a 

 round polished tubercle on the breast of the male. This species was discovered by Cranch, and 

 Leach, writing after the death of that assiduous collector, was uncertain whether he had found it on 

 the coast of Devon or Cornwall. 11 Couch, taking from Milne-Edwards the name /. leptorhynchus, 

 calls it the ' Small-snouted Inachus,' but is evidently not quite clear about the species or any Cornish 

 locality for it. 12 Cocks however notes it under its proper name from ' Trawl refuse ; not uncommon,' 

 and adds ' September and, 1 848, Dr. Vigurs found six males and one female in a small basket of 

 refuse. A male in my cabinet measures 9 in. from toe to toe.' 



The family Hyadidae takes its name from Hyas, established by Leach as the third genus in a 

 division, of which Eurynome was the fourth, Blastus the fifth, and Pisa the sixth, the last two being 

 now recognized as identical. Hyas araneus (Linn.), and H. coarctatus, Leach, do not appear in 

 Couch's Fauna, but Cocks records both from ' Harbour, Carrack Roads, trawl refuse ; not uncom- 

 mon.' The specific name of the second species refers to a much stronger lateral constriction of the 



I Report of the Committee appointed to explore the Marine Fauna and flora of the South Coast of Devon 

 and Cornw. Recorder, C. Spence Bate. Brit. Assoc. Report for 1865 (1866), p. 52, the Committee included 

 Jonathan Couch and others. 



' Decapoda du Talisman et du Travailleur, p. 162. 



* See Alcock, Journ. Asiat. Soc. Bengal (1895), vol. Ixiv, pt. ii, pp. 160, 161. 



* Brit. Stalk-eyed Crustacea, p. 4. 6 Malac. Podophth. Brit. (1815), text to PI. XXIII. 

 6 Fauna, p. 64. 7 Malac. Podophth. Brit. (1815), text to PL XXII'. 



8 Fauna, p. 65. Ibid. w Ibid. 



II Malac. Podophth. Brit. (1817), text to PL XXII*. " Fauna, p. 65. 



263 



