1906. J MOLLUSKS FROM THE PERSIAN GULF. 801 



Superficially it is somewhat akin to Myt'das cuhiius Say, found 

 by one of us on the shores of Flox-ida several years ago, and like- 

 wise to if. charpentieri Dunker, from West Africa, but in oui- 

 opinion is sufficiently distinct from all its congeners to merit a 

 separate description. Mr. A. J. Jukes-Browne, to whom our 

 thanks are due for having examined our specimens, considers it, 

 with M. cubitus Say, charj)entieri Dki-., and othei's formei'ly 

 considered Mytili, as belonging to the genus Brachyodontes Sw., 

 subgenus Hormomya (Morch) *. 



Crenella adamstana, nom. nov. (Plate LY. fig. 2.) 



Grenella decussata A. Ad. Proc. Zool. Soc. 1870, j). 7, non 

 Montagu. 



Cryptodon decttssatus Ad. 



P.G. Gulf of Oman, Maskat. 15 fathoms. 



M.C. Dredged in various places, at 10 to 15 fathoms. 

 I. Karachi. 



This is not, as was thought by Dr. Arthur Adams, identical 

 with the British and Northei-n Atlantic species, and therefore 

 requires a name. 



Crenella pr.ecellens Melvill, sp. n. (Plate LV. fig. 4.) 



0. testa temti, albida vel jjcdlide hrawaea^ suhohliqua, profn/nde. 

 Gonvexa, pyrifo7nm, siope?'ne latiore^ undique radiatim pulchre 

 tenuiUrata, lineis concentricis incre7nentalibus fortiter prcudita, 

 anticefere recta, 2^ostice obliqua, ad margineni ventralem sensim 

 delabente; ttmbonibtcs parvidis, linea cardinali in valva sinistra 

 paulluvi promimda, dentiformi ; pagina interna alba, mar- 

 ginibus mimotissime crenuliferis . 



Alt. 8, lat. 6, diam. 5 mm. 



Hah. Persian Gulf: Gulf of Oman. Lat. 24° 58' N., long. 

 56° 54' E. ; 156 fathoms, shell-sand. Maskat, 15 fathoms. 



From the last-mentioned place come small, perfect examples, 

 pale brown in colour. 



A beautiful sjjecies, the fine radiating lirse, crossed with repeated 

 concentric incremental lines of growth, being conspicuous ; the 

 form pear-like, wdiile within a tooth-like jDrojection attached 

 to the hinge-plate is noticeable in the left valve, the whole internal 

 margin being crenulate. The valves are profoundly convex and 

 swollen ; some variation existing as regards depth and width of 

 convexity. 



MoDiOLARiA calceata f, sp. n. (Plate LY. fig. 3.) 



M. testa parva., anguste oblongo-rhomboidea, albida, inrnqiii- 

 laterali, convexa, lateribus fere rectis ; umbonibus parvisy 

 paulhivi incurvis, bina serie striarum radiatim disposita^ 

 antice sionul ac p)ostice, inter quas superficie concentricis incre- 



* Proc. Mai. Soc. vol. vi. p. 223. 



f Calceus, a shoe, from the very convex ol)long form. 



