SCUTELLINA. 127 



Family SCUTELLINID^E Dall. 



Shell ovate, depressed-conical, surface with radiating sculpture or 

 cancellated ; apex posterior and submarginal ; muscle-impression 

 horse-shoe-shaped, open in front. 



The dentition is purely rhipidoglossate, resembling that of Neri- 

 tina and Helicina. The gill is situated like that of Neritina or 

 Acmcea, on the left side above the body, and pointed to the right 

 over the back of the neck. The anal papilla and that by which the 

 products of the renal organ are ejected, are situated exactly as in 

 Acmsea. The tentacles are long and slender, the eyes well-devel- 

 oped and placed on swellings at the outer posterior part of the ten- 

 tacles. The distal end of the muzzle is expanded, seinilunar, smooth, 

 with a continuous margin a little produced at the outer corners. 

 The mouth is small and situated in the center of the disk. The 

 dental formula (for a half-row) is 1. (1. 2. 1.). oc . The rhachidian 

 tooth is flat, squarish, and edentulous, as in Helicina orbiculata. 



Shells of this family may be known from Patellidce and Acmcei- 

 dce by the posterior position of the apex, which is directed away from 

 the opening in the horse-shoe-shaped muscle-scar, while in the fam- 

 ilies mentioned the apex is more or less anterior, at the same end 

 that the muscle of attachment is open. Broderipia has a very sim- 

 ilar shell, but it is pearly inside, while Scutellina is not. Anatomi- 

 cal characters as well as the limpet-like shell seem to throw the three 

 families Scutellinidce, Addisoniidce and CocculinidcB into proximity; 

 but there are other features sufficiently isolating each. It must be 

 understood that their natural position is by no means between Hal- 

 iotidce and Fissurellidce, families with which these little limpets 

 have no especial affinity. 



According to Dall, there is no relic of epipodium nor any intro- 

 rnittent organ in the specimen of S. antillarwn described by him, 

 which may have been, however, a female. The margin of the man- 

 tle has a minute fringe of papillae. 



Genus SCUTELLINA Gray, 1847. 



Scutellina GRAY, P. Z. S. 1847, p. 168 (type S. crenulata Brod.). 

 DALL, Amer. Journ. Conch, vi, p. 236. H. & A. AD. Gen. Rec. 

 Moll, i, p. 460. DALL, Bull. M. C. Z. xviii, p. 342, 1889Scutella 

 BROD. P. Z. S. 1834, p. 47 (not of Lamarck). 



