ACADEMY OF NATUKAL SCIENCES. 213 



tis ; tota superficie squamulis subquadratis seriatim ornata ; seriebus ar. centr. 

 longitudinalibus, ar. lat. et valv. terra, radiantibus, creberrimis, hand interruptis ; 

 jugo elevato, sub-acuto ; umbonibus incouspicuis ; marginibus umbonalibus vix 

 inflectis, lateralibus vix a squamulis serrulatis ; mucrone conspicuo, raediaDO : 

 intus, laminis centralibus valde lobatis, sinu maxirao, planato ; lain, insertionis 

 obsoletis : pallio, squamulis paleatis, striatis, confertis instructo ; pilis elatiori- 

 bus aciculinis, crystallinis, hue et illuc et circa marginem ornato. 



Long. 0-30, lat. 0-18 ; div. 90°. 



Hab. Catalina Island, 10-20 fm., Cooper. 



The appearance of this northern genus among the Mopalire and Ischnochitons 

 is very remarkable ; as is the character of the mantle-margin. 



Genus Nacella, Schumacher. 

 Nacella (? palleacca, var.) triangularis, Cpr. State Coll. No. 416c. 



N. t. "N. palleacca" simili, sed multo minus elongata. ; apice elato, marginibus 

 rectangulatim divergentibus ; albida, raaculis fuscis perpaucis ornata ; striulis 

 subobsoletis. 



Long. 0-28, lat. 0-12, alt. 0-18, div. 90°. 



Hab. Monterey, 4 dredged dead, Cooper. 



Probably a distinct species. The solitary shell sent by Dr. Cooper is shaped 

 like a right-angled triangle, with five large brown spots near the base. 



? Nacella subspiralis, Cpr.? n. s. State Collection, 4166. 



? N. t. parva, carnea, laevi, tenuissiraa ; vertice " Emarginulce " siraulante, 

 subspirali, sed apice patelloideo, adunco ; t. adulta valde elevata ; margine lat- 

 erali autico subrecto, apice projicicnte, valde remoto ; postico maxime fornicato ; 

 aperturas margine antice et postice prolongate 



Long. 0.26, lat. 049, alt. 0-20, div. 80°. 



Hab. Catalina Island, 10-20, fm., 4 dead, Cooper. 



This may be the young of the long-lost Patella calyptra, Mart. It may be 

 a Scutellina. Even the genus cannot be predicated from the shell alone. 



Genus AcxiiEA, Eschholtz. 

 Acmcca (? pileolus, var.) rosacea, Cpr. 



A. t. parva, conica, tenui, lgevi ; t. jun. pallide rosacea, elegantissime maculis 

 albis et fuscis subradiatim sparsis ; t. adulta strigis fusco-rosaceis et albidis 

 picta ; apice elevato, parum autico ; intus rosaceo. 



Long. 0-20, lat. 0.16, alt. 0-08, div. 100°. 



Hab. San Diego, 1 sp. jun. (Palmer) : Monterey, 1 dead sp. Cooper. 



The absence of stria?, very thin texture, and regularly conical growth, dis- 

 tinguish this shell from A. patina, a rare variety of which has a pinkish tinge. 

 Specimens in Mus. Cuming are marked "pileolus, Midd.," but do not accord 

 with the diagnosis. It is almost exactly like Herm* specimens of A. virginea. 

 Col. Jewett's similar shells, marked " Panama," were perhaps West Indian. 



* A small island in the British Channel. 



