106 COLLECTIONS FROM MELANESIA. 



before mc gradations in respect to length and breadth. Both are 

 slightly narrower in front than behind, sculptured with fine con- 

 centric striae and more or less indistinct shallow radiating markings, 

 a feature unnoticed by Deshayes. Although the dentition is 

 described by that author as somewhat different, I am bound to Bay, 

 after a most careful examination, that both the number and position 

 of the teeth are absolutely similar. In the left valve I find three 

 teeth, the anterior one being very small at the termination of the 

 inner margin of the hinge-plate, which is grooved on both sides of 

 the beak. The central tooth is large, prominent, situated imme- 

 diately beneath the point of the umbo, and the third is insignificant 

 and posterior to the narrow oblique ligament. The right valve has 

 a large prominent tooth a little in front of the apex of the umbo, 

 and generally the extremity of the inner edge of the grooved hinge- 

 plate is raised into a tooth-like prominence behind the ligament, 

 which extends not only within the valves, but also along the hinge- 

 line just above the teeth. The single specimen from Port Molle and 

 'one in the Cumingian collection are peculiar in having two or three 

 of the shallow radiating impressions towards the hinder ventral ex- 

 tremity deeper, thus producing a wavy margin to the valves at that 

 particular spot. 



47. Scintilla aurantiaca. (Plate VII. figs. H, HI.) 



Deshayes, Proc. Zool. Soc. 1855, p. 179 ; Soicerby, Thes. Conch, vol. iii. 

 p. 170, pi. 234. fig. 5. 



Hah. North Australia, under stones at low water (Juices) ; island 

 of Xairai, Fiji, at low water (Brit. Mus.) ; Port Molle, Queensland 

 (Copplmjer). 



The specimens from Port Molle agree precisely with the types of 

 8. aurantiaca in the national museum. There are some other species 

 which I cannot distinguish from it; these are 8. faba, Desh., S. 

 Forbesii, Desh., 8. pallidula, Desh., 8. ambigua, Desh., 8. bornei nsis, 

 Desh., and 8. adamsi, Desh. The last and 8. faba are placed by 

 Sowerby in the group of " species with no hiatus" in the ventral 

 margin. This location is incorrect, for both gape slightly, and in 

 fact Deshayes, in his description of the latter, says " margine infe- 

 riore angustissme hiante." This opening appears to be subject to 

 variation in shells which are unquestionably the same specifically j 

 and therefore I believe it probable that all the above-mentioned 

 so-called species will prove to be variations of Lamarck's Psam- 

 bia aurantia, which, according to Sowerby's figure (Conch. Icon, 

 fig. 20, 8. mauritiana), has an extremely wide gape beneath. The 

 latter species is said to be synonymous with 8. aurantia by Deshayes 

 (Anim. sans Vert. vol. vi. p. 180, Galeomma aurantia), and von 

 Martens expresses a similar opinion (Mobius, ' Meeresfauna Mauritius 

 &c.,' p. 322). Deshayes (P. X. S. 1855, p. 167) says that the La- 

 marckian shell is a Galeomma. 



The animal of Dr. Coppinger's shells agrees with the description 



