1922] 



NATURAL SCIENCES OF PHILADELPHIA. 



53 



appear to be marked off proximad by a slight groove, so that they 

 have much the appearance of large, triangular cusps. The small 

 form is the one figured; it has a much smaller number of the mar- 

 ginals (80 as against 106), and the comb-lateral has one more 

 cusp and all are longer and narrower than in the larger form. 

 This species is apparently quite closely related to H. neritella. 



The operculum of this group is very similar to that of Tristramia, 

 s. s. It has a heavy, reddish, horny plate, and a thin calcareous 

 plate; the latter is somewhat thickened towards the columella!- 

 but incomplete towards the palatal margin. Although the group 

 certainly belongs with Tristramia, it is rather divergent and needs 

 further study before any accurate estimate of its relationship 

 can be stated. As already remarked, there are certain resemblances 

 to Tamsiana, and it is possible that the two groups connect up in 

 the lesser Antilles. Many of the species included in Subglobulosa 

 A. J. W. and F estiva A. J. W. have the yellowish operculum, with 

 the poorly-developed horny plate, which is more characteristic 

 of Oligyra than of this group. 



Table III. Radular Formulae in Helicina, Lucidella, 



and Schasicheila. 



Centrals Comb Marginals. Grand 



A B C Lateral 2 3 4 5 Total Total 



H.amoena 5 5 4 9-10 6 4 6 70 151 



H.cinctdla 5 6-8 4 9 4 6 5 83 177 



H . concentrica 5 4 5 11 1* 3+4 7 79 169 



H. tamsiana appuni 4448 5 35 87 185 



H.nemoralis 4 5 4 9-10 5 2 7 108 227 



H.caracolla 1-2 5 4 10 3 5 8 83 177 



H.r.ernesti 6 2 9-10 2 14 5 89 189 



H. tenuis 6 4 7 1* 1+8 5 5 70 151 



H.zephyrina 7 1 8 2* 1+7 5 5 102 215 



H. neritella 3 64 7 1*2 +6 ?? many many 



H.adsptrsa 3 4-5 4 9 2* 3+4 5 7 106 223 



S.silacea 4 4 4 9-104 5 6 9 78 167 



S.sagraiana 4 4 4 9 2* 1+6 6 8 80 171 



S.ciliata 4 4 4 6 1 8(5)* 4+9 58 127 



S.hidalgoana 3 4 4 6 9 6 5 46 103 



L.venezuelensis. . . . 4549 7 40 91 



L.lirata 2 7 6 6 5 12 62 135 



L. aureola 1 7 5 9-10 2 21 20 136 283 



Genus LUCIDELLA Swainson. Tropical America. 



?Subgenus LINDSLEYA Chitty. Jamaica to South America.? 



Lindsleya Chitty (1857). Type Stoastoma lindsleyanum C. B. Adams 

 1849) Jamaica. 



