SYKES : SOUTH AFRICAN CHTTONS. 133 



Binoplax gigas, Gmelin, 1788. Linn. Syst. Nat., ed. 13, p. 3206. 

 Table Bay, Natal, Port Elizabeth, etc. Valve-slits : anterior and 

 posterior 8-10, median 1. A very striking and well-known species. 



75c7woc7/«Vo?iOM/«ms, Krauss, 1848. Die Sudafrik. Moll. p. 39. Natal 

 (Krauss) ; Lea Point, near Cape Town (" Challenger," as /. viriduhis, 

 Couthouy) ; Tristan d'Acunha (Pilsbiy, as /. Macgilli tragi, Cptr. 

 MS.). I have carefully removed and inspected a median valve of 

 the "Challenger" specimen, and fi'om the fact that it has only one 

 median slit I am convinced that it is not /. viridulus, which has 

 from two to three median slits, and therefore belongs to the section 

 Radsielln. I am unable to separate the sheR from /. oniscus. I have 

 had a series of specimens given me said to have been named by Mr. 

 Sowerby " Cliiton marginatus, Pennant " ; these also I consider to be 

 I. oniscus} Mr. Pilsbry^ has described a species from Carpenter's 

 MSS. as/. Macgillirragi, citing two tablets from Tristan d'Acunha, and 

 one from St. Paul's, in the Cuming Collection in the British Museum 

 (Natural History). The Tristan d'Acunha shells are, I think, I. oniscus, 

 and have valve-slits, anterior and posterior 13, median 1 ; the St. Paul's 

 shell is very nearly allied, but distinct, and has valve-slits, anterior 

 12, median 1, posterior 11. This last specimen also agrees with 

 Carpenter's dimensions, and I therefore regard it as the type of 

 I. Macgillivragi. There is another tablet also from St. Paul's, Indian 

 Ocean, collected by Macgillivray on the voyage of the " Herald," and 

 received by the Museum in 1859; Cuming's specimen probably came 

 from this source. The indistinct radiating wrinkles on the median valves 

 of /. Macgillivragi assist in separating them. Mr. Sowerby recorded 

 /. Macgillivragi, from the Cape, in his work ; at this time no descrip- 

 tion of the species had appeared, and he was probably trusting to the 

 tablets in the British Museum (Natural History). According to 

 Ki'auss the valve-slits in /. oniscus are: anterior and posterior 10, 

 median 1. The habitat of "Orange Harbour, Cape of Good Hope," 

 given in the " Challenger " Eeport, is of course an error for " Orange 

 Harbour, S. America." 



Ischnochiton lentiginosus, Sowerby, 1840. Charlesworth's Mag. Nat, 

 Hist. iv. p. 293. Cape Coast (Krauss, as C. cganeopunctatus) ; Australia 

 (Dr. Dieffenbach) ; Port Hackin, New South Wales (Dr. Cox). Mr. 

 Pilsbry^ states that "except in being somewhat larger, and said 

 to be from a different locality, this seems to be absolutely the same as 

 7. cganeopunctatus, Krauss. " It is likely that the Australian habitat 

 assigned to lentiginosus is a mistake." * 'The British Museum (Natural 



^ Since this paper was read Mr. Pilsbry has described ("Nautilus," vol. viii. p. 9) 

 specimens from, in all probability, the same source, under the name of Ischmchiton 

 Elizabethensis. My specimens appear to be punctate rather than, as he states, 

 granulate ; but I forbear further comment as I have no authentic specimens of 

 /. oniscus before me. 



^ Man. Conch, ser. I. vol. xiv. p. 101. 



3 Ibul. p. 135. 



* See, however, Man. Conch, ser. I. vol. xv. p. 82, published since this paper 

 •was written and read. 



