EMARGINULA. 477 



bearing two subulate tentacles with subpedunculated eyes 

 at their external bases ; a range of cirrhi around the sides 

 at the base of the foot ; mantle simple-edged ; anal siphon 

 with its angulated membranous sides projecting from the 

 edges of the fissure ; branchial plumes two. Tongue (ac- 

 cording to Loven) with numerous transverse dental ele- 

 ments ; its rachis composed of nine teeth, the central one 

 laminar and subf[uadrate, the lateral teeth {uncmi) very 

 numerous. 



Loven suggests that an isolated cirrhus which is present 

 on the back of the foot in this genus (and which we have 

 observed also in Puncturella) may be a rudimentary oper- 

 culigerous lobe. 



This is a genus of ancient appearance within our area, 

 where species of it were present during the older secondary 

 period, if not before. Those now living enjoy a great 

 range in depth. 



E. RETICULATA, Sowcrby. 



Clatbrated; vertex but little recurved in the adult, always fall- 

 ing within the basal circumference ; fissure short and narrow, 



Plate LXIII. fig. 1, as Mlilleri, 



Lister, Hist. Conch, pi. 543, f. 28. 



Patella fissiira, Linn. Syst. Nat. ed. 12, p. 1261 (only in part and not well). — 

 Penn. Brit. Zool. ed. 4, vol. iv. p. 144, pi. 90, f. 152. — Da 

 Costa, Brit. Conch, p. 11, pi. 1, f. 4. — Pulteney, Hutchins, 

 Hist, Dorset, p. 51.— DoNOV. Brit. Shells, vol. i. pi. 3, f. 2. — 

 Mont. Test. Brit. vol. ii. p. 490 (adult).— Maton and Rack. 

 Trans. Linn. Soc. vol. viii. p. 235 (in part). — Rack. Dorset 

 Catalog, p. 59, pi. 23, f. 4.— Turt. Concli. Diction, p. 141.— 

 MtJLLER, Zool. Dan. pi. 24, f. 7, 8.— Brookes, Introd. Conch. 

 f. 127.— DiLLW. Recent Shells, vol. ii. p. 1054.— Wood, 

 Index Testae, pi. 38, f. 86.— Mawe, Linn. Conch, pi. 32, f. 1. 



Emaryiuula reticulata, J, Sowerby, Min. Conch, pi. 33, lower figs, (fossil). 



„ fissura, FtEMiNii, (not Lam.) p. 365 (in part, not var.). — Johnston, 



