41 137 



phagiis" from St. Maurice and Bourbon agrees exactly with L. gracilis, Phil., but yet 

 Phu.iimm and Dunkeh refer it to L. teres, Phil.). Dunkeu' thinks that L. teres is 

 closely analogous to L. niger, d'Orb. (= L. Antillarum, Phil.), and is perhaps only a 

 variety of the same. The reason for this must be sought in the opinion expressed 

 in his diagnosis of L. teres, Phil.: "epidermis nigro-castanea, in dorso ct subler 

 umbonibus laevis, in latere ventris simili modo striata ac in Lithophaga nigra." 

 The most important mark of distinction between the West Indian L. niger, d'Orb., 

 and the East Indian L. gracilis, Phil., is, as far as I can see from the material at 

 my disposal, precisely this epidermal striation. In L. gracilis, Phil., these trans- 

 verse lines extend almost to the anterior end (diminishing gradually in size) and 

 only a small portion of the outermost part of that end is quite smooth; in 

 the posterior part, the striation is usually continued somewhat farther than in 

 L. niger. On comparing two specimens — one of each of these species — of equal 

 size (e.g. 49 mm.), the result will be as follows: in L. niger (from St. Thomas) the 

 striation is continued bej'ond 32 mm., as measured along the lower margin of the 

 shell, while in L. gracilis (from the Gulf of Siam) it covers 40 mm. 



Lithodomus straminea, Dunker. 



Lithodomus stramineiis, Dunrer, Reeve, Conchol. icon, X, Lithodomus, Sp. 11. 



Lithophaga straminea, — Dunker in Martini u. Cmkmnitz, Conchyl. Cabin., VIII, .'i Abth. A, p. fi, 



pi. 2, figs. 1—2. 



Koh Chang, very low tide (1). 



Long. 22 mm. 



Distribution:— Madras (Melvill & Standen), the Gulf of Manaar (Thurston). 

 — Mast Head Reef, Queensland (Heoeev). 



The habitat "West Indies" given in Cuming's collection, is undoubtedly due 

 to an error. 



J. Marille and G. le Mesle record" Lithodomus lithophagiis L. from Poulo 

 Condor; Crosse^ is right in doubting the correctness of this determination. Is it 

 not more probably L. straminea, Dkr., that has been found? 



Lithodomus Malaccana, Reeve. 



Lithodomus Malaccana, Reeve, Conchol. icon., 1858, X, Lithodomus, Sp. 20. 



Lillxoplutga Malaccana, — Martini u. Chemnitz, Conchyl. Cabin., VIII, 3 Abth. A, p. 2(», pi. \, fig. 1. 

 Litlwdomiis sabula, — Conchol. icon., X, Lithodomus, Sp. 26. 



Lithophaga — — Martini u. Chemnitz, Conchyl. Cabin., VIII, 3 Abth. A, p. 21, pi. V, fig. 13 



(figs. 11 — 12?). 



— cavernosa. Dunker, Martini u. Chemnitz, Ioc cit., p. 7, pi. II, figs. 5— 6; pi. V, figs. 15— Hi. 



— reticulata, — — Ioc. cit., p. 19, pi. V, figs. 9- 10. 



' Martini u. Chemnitz, Conchyl. Cabin., VIII IJd., 3. Abth., p. 13. 

 ■î Journal de Conchyl., XIV, 18(i6, p. 118, 

 ä Ioc. cit. p. 119. 



1). K. L). Vi.lcnsk. Selsk. Skr., 7. Ra-klie, nalurvidensk, :>]i mnllu-m. AM V. 3. 18 



