68 THE VOYAGE OF H.M.S. CHALLENGER 



The small specks on the shell which Mr E. A. Smith refers to above as yellow are white on the 

 Challenger specimen. An interesting variation of this same kind occurs in a specimen of Trochus 

 (Diloma) fuligineus, A. Ad., in the Challenger collection, in which the minute specks, which are 

 usually yellow, are on the most of the shell white, but are yellow on the last part near the mouth, 

 where the shell has been broken and repaired. 



The operculum of Trochus porcifcr, which Adams does not mention, is that of a typical Trochus, 

 being thin, horny, of many whorls, whose edge forms an imbricated flange on the outer face of the 

 operculum. 



27. Trochus (Oxystele) euspira (Dull.) 



Margarita (?) euspira, Dall, "Blake" Dredgings, Bull. Mus. Comp. Zool., vol. ix. pp. 44, 102. 

 Trochus (Oxystele) euspira, Jeffreys, "Lightning" and "Porcupine" Moll., Proc. Zool. Soc. Lond., 

 1883, p. 98, sp. 10, pi. xx. fig. 6. 



Station 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. Off Culebra 

 Island, West Indies. 390 fathoms. Pteropod ooze. 



Habitat. — North Atlantic, 740 to 1095 fathoms (Jeffreys), Gulf of Mexico, 805 fathoms 

 (Dall). 



28. Trochus (Photimda) ccerulescens (King). 



Margarita ccerulescens, King, Zool. Journ., vol. v. p. 346, No. 54. 



Trochus Uneatus, Philippi, Arehiv f. Naturgesch., 1845, p. 66, sp. 50 (not of Da Costa). 



„ c&rulescens, Philippi, Conch. Cab. (ed. Kiister), p. 250, sp. 321, pi. xxxvii. fig. 11. 

 Margarita maxima, Hombron and Jacquinot, Pole sud, p. 59, pi. xiv. figs. 32, 33 (not TrocJius 



maximus, Koch). 

 Photina ccerulescens, A. Adams, Monog. Trochid., Proc. Zool. Soc. Lond., 1851, p. 191, sp. 2. 

 Photinula ccerulescens, Adams, Genera, voL i. p. 427, pi. xlviii. fig. 9. 

 Margarita cwrulesce?is, Sowerby in Keeve's Conch. Icon., vol. xx. pi. ii. fig. 12. 

 Trochus hombroni, Fischer in Kiener's Iconog., p. 320, sp. 185, pi. c. fig. 3. 



Station 315. January 26, 1876. Lat. 51° 40' S., long. 57° 50' W. Port Stanley and 

 Port William, Falkland Islands. 5 to 12 fathoms. Sand and gravel. 



Habitat. — Straits of Magellan (Philippi), Falkland Islands (Fischer). 



This species has suffered much in the matter of its name, and I greatly fear that consistency 

 requires those who maintain the integrity of Linne's genus to follow Dr Fischer in calling it Trochus 

 hombroni, though kingi would have been a more generous choice of name. I have retained the oldest 

 name because Deshayes has thrown some doubt on the Trochus ccei-ulesccns, Lam. (see Anim. s. vert., 

 2d ed., vol. ix. p. 135, note), and in the present uncertainty of all nomenclature, it is not impossible 

 it may have right to survive. 



King's species differs from Trochus (Photinula) tccniatus. Sow., not only in colour, but in form. 

 It is in particular more depressed, the spire being much less exserted : the pillar is very much shorter, 



