TRO CHITA. 



Plate I. 



(Jemis TllOCHITA, Schumacher. 

 Testa conica, interditni suispiralis. Appendix interna nunc 

 lateralis, effusa, nunc trochoidea, ad marginein pro- 

 duct a. 

 Shell conical, sometimes subspiral. Internal appendage 

 somewhat lateral and effused, sometimes trochoid, 

 reaching to the margin. 

 After assigning to the genera CaJyptrma, Crucibulum., 

 and Crepidula the members of this family respectivelj' 

 characterized by the presence of a basal plate, by a cen- 

 tral cup, and by a transverse septum, there remain about 

 fifteen species, in which the internal appendage assumes 

 a spiral septum or trochoid form. For these Professor 

 Schumacher founded the genus Trochita. In some, as in 

 T. radians, spirata, and clypeolum, the internal appendage 

 reaches to the margin ; in others, as in T. conica, sub- 

 rejtexa, and Sinensis, the appendage is comparatively small, 

 lateral, and effused. These last constitute Dr. Gray's 

 genus Galerus. 



The western coasts of South and Central America and 

 New Holland are the principal habitats of the genus. 

 One species is found in Britain, but only on the southern 

 shores. 



Species 1. (Pig. a, 6, Mus. Cuming.) 

 Trochita poculdm. Troch. testa orliculari, pikiformi, 



rertire elato ; alM ; appendice interna spiraliter septi- 



formi. 

 The little-cup Trochita. Shell orbicular, cup-shaped, 



vertex raised ; while internal appendage spirally 



septum-shaped. 

 Hab. Valparaiso; Cuming. 



A small, rounded, cap-shaped species, distinct in form 

 from any of those described by Mr. Broderip. The outer 

 surface is covered with a parasitic coralline. 



Species 2. (Mus. Cuming.) 

 Trochita pellucida. Troch. testa orbiculari, dcpressius- 



culd, siibtiliter concerdrice striata, vertice centrali ; 



alba, pellucidd ; appendice interna subdepresso-septi- 



formi. 

 The teanspabent Tkochita. Shell orbicular, rather 



depressed, finely concentrically striated, vertex central; 



livid-white, transparent ; internal appendage rather 



dcpressly septum-shaped. 



Hab. Philippine Islands ; Cuming. 



A small, livid, transparent species, rather depressed. 



Species 3. (Pig. a, b, Mus. Cuming.) 



Trochita radians. Troch. testa orbiculari, subdepressa, 

 coslis subnodtilosis nndique radiatd ; albidd, intiii in- 

 terdum castaneo-nigro tinctd, exlus epidermide Itites- 

 cente fibrosa induta ; subtm concavd, appendice in- 

 terna perampld, Trochiformi. 



The radiating Trochita. Shell orbicular, rather de- 

 pressed, rayed throughout with slightly nodiUous 

 , ribs ; whitish, somelimes stained witliin with chest- 

 nut-black, covered without with a yellowish fibrous 

 epidermis ; concave beneath, internal appendage very 

 large, Trochus-shaped. 



Crepidula radians, Anim. sans vert. vol. vii. p. 626. 

 Trochus radians, Lamarck. 

 Infimdihulum radians, Sowerby. 

 Cah/ptraa Peruviana, Deshayes. 

 Testa juvenis, Trochita ventricosa, Carpenter. 



Ilab. Valparaiso ; Cuming. 



This species, described originally by Martini, among 

 others of the group, without any specific name, under the 

 general head of Lepas, was placed by Lamarck in his 

 genus Trochm. ]\I. Deshayes was the first to perceive its 

 true affinities. 



Species 4. (Pig. a, b, Mus. Cuming.) 



Trochita aspersa. Troch. testa orbiculari, tenuiculd, 



concenlrice tenuistriatd, vertice subspirali ; pellucido- 



albd, intus rufo maculaid ; appendice interna laterali, 



appresse effusa. 

 The sprinkled Trochita. Shell orbicular, rather thin, 



concentrically finely striated, vertex somewhat spiral ; 



transparent-white, spotted within with red ; internal 



appendage lateral, appressly effused. 

 C. B. Adams, Ann. Lyceum Nat. Hist. vol. v. p. 443. 

 Hab. Panama (under stones, at low water-mark) ; C. B. 



Adams. 

 Of semitransparent substance, conspicuously painted in 

 the interior with red spots ; but of a somewhat fainter and 

 less clouded character than those in T. conica. 



