A HISTORY OF CORNWALL 



bivalved or simple shield, and with some of the appendages behind the mouth normally branchial ; 

 the Copepoda have normally a segmented body, not enclosed in a bivalved shell-covering, the seg- 

 ments not exceeding eleven, the limbs not branchial. 



The Branchiopoda are divided into orders, of which the Phyllopoda here claim our attention on 

 account of a single species in the family Branchipodidae. This family belongs to a group in which 

 the body is long and flexible, without shield, and the eyes are stalked and movable. Of the species 

 in question Mr. Rupert Vallentin says, ' In a roadside pool, near the entrance of Enys, I found 

 numerous specimens of that interesting crustacean Chirocephalus diaphanus, Prevost. I have been 

 informed by my friend Mr. W. Garstang, of the Plymouth Marine Biological Association, that " a 

 gentleman in Plymouth, many years ago, secured some specimens of Chirocephalus in a road-side 

 pond near Grampound road." This is the only record I have been able to find of Chirocephalus 

 occurring in Cornwall.' J This large and beautiful entomostracan is widely distributed over England. 

 Its eggs lie in wait in dried mud, to hatch out when kindly rain provides a pool however shallow. 



The ' branching-horned ' order Cladocera is more amply represented than the phyllopods. 

 Named from their two-branched second antennae, these little animals are like the Ostracoda in having 

 a bivalved test or shell-covering, but unlike them in having the head distinct. While Chirocephalus 

 can boast of having eleven pairs of feet, the number of pairs in the Cladocera ranges only from four 

 to six. There are two sections Calyptomera and Gymnomera. The former contains a tribe called 

 Anomopoda, because its feet are not all similar, the front ones being more or less prehensile, with- 

 out branchial laminae. This great tribe is divided into four families, at the head of which stands 

 that of the Daphniidae. To this belongs Daphnia pulex (de Geer), which Cocks reports from ' Ponds 

 Budock bottom, moorstone quarry : in trough near Mr. Jago's farm cottage, Trevethan, etc. 2 He 

 adds 'var (D. psittacea, Baird), water-trough, Jago's farm, &c.' Dr. G. S. Brady, who in 1898 

 transferred Daphnia magna, Strauss, to a new genus, Dacty/ura, records that species from Tresco in 

 the Scilly Islands, and appends a note, ' Daphnia psittacea, Baird, is quite unknown to me, though 

 noted by some continental authors.' 3 As Daphnia vetula (Mttller), Cocks reports the species since 

 known as Simocephalus vetulus (O. F. M.), but now as Simosa vetula,* from ' Pond near dog-kennel, 

 Panscouth lane ; ditch, Gwyllyn-vase, etc.' To the next family Bosminidae belongs Bosmina 

 longirostris (O. F. M.), which Cocks found 'In water from a ship's tank, just arrived from London : 

 1853.' So far therefore the species can only be regarded as an immigrant, but it is in truth widely 

 distributed, and recently Mr. Rupert Vallentin, F.L.S., has recorded this and various other entom- 

 ostraca from the Looe Pool in the north-eastern extremity of Mount's Bay. The Macrotrichidae are 

 without a recorded representative. The fourth family, the Chydoridae, furnishes the tiny animated 

 globe Chydorus sphaericus (O. F. M.), from ' Ponds, College wood, etc.' ; Eurycercus lamellatus 

 (O. F. M.), from ' Stagnant water, Budock bottom, near stone quarry ' ; Alona quadrangular'^ 

 (O. F. M.), from ' Stagnant pools, Pennance, Budock bottom, etc.' ; and Pleuroxus trigonellus 

 (O. F. M.), from ' Boggy ground near Trigonigg Farm.' 



The section Gymnomera, with a carapace too small to cover the thoracic feet, in its tribe 

 Onychopoda has but a single family, the Polyphemidae. Here there are only four pairs of feet and 

 the eyes are conspicuously large. Polyphemus pediculus, de Geer, is reported by Cocks from ' Stag- 

 nant water in butt ; ditch, Gwyllyn-vase, etc.' All the above are freshwater species. A marine 

 entomostracan is recorded by Mr. Vallentin, who in his Additions to the Fauna of Falmouth 

 already quoted says, ' Evadne normanii, Loven, is to be found in tow-net gatherings at most 

 seasons of the year.' The species belongs to the family Polyphemidae, and should be written Evadne 

 nordmanni, Lovn. 



The Ostracoda are divided into two tribes, the Myodocopa, which almost always have a rostral 

 sinus to their shells, and almost always have a heart, and the Podocopa which have neither. Three 

 families of the former exclusively marine tribe come under consideration. The Asteropidae, which 

 have compound lateral eyes and are distinguished from all other Ostracoda by seven pairs of long 

 branchial leaves folding over the extremity of the animal, here possess two species of the genus 

 Asterope, namely, A. mariae (Baird), found at Penzance by Norman, at the Scilly Isles by Brady and 

 Robertson, 5 and A. teres (Norman), taken at the latter locality by the same companions. There also 

 they obtained Philomedes interpuncta (Baird), of the family Cypridinidae, the eyes of the female in 

 this genus being small or wanting, those of the male well developed. 6 In the Polycopidae, which 



1 ' Additions to the Fauna of Falmouth,' in the Fifty-Ninth Annual Report of the Roy. Cornw. Polyt. Soc. 

 1891 (1892), p. 97. 



* ' Contributions to the Falmouth Fauna, Entomostraca.' The Twenty-Fourth Annual Report of the Royal 

 Cornw. Polyt. Soc., 1856 (1857), pp. 15-19 All the quotations from Mr. W. P. Cocks on Entomostraca 

 are from this paper. 



3 Trans. Nat. Hist. Northumberland, etc. (1898), vol. xiii, pt. z, pp. 243, 244. 



4 Norman, in Ann. Nat. Hist. (1903), Ser. 7, vol. xi, p. 367. 



5 Brady and Norman, in Trans. Royal Dublin Soc. (1896), Scr. 2, vol. v, p. 633. 6 Ibid. p. 653. 



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