2 Dr. P. P. Carpenter on new Forms of MoUusca 



tim eleganter variegata ; striis incrementi concentricis, postice ex- 

 tantioribus ; umbonibus postice flectentibus, obtusis ; parte antica 

 prolongata, regulariter excurvata ; marginibus dorsali et ventrali 

 subparallelis, subrectis ; parte postica curtiore, subangulata : intus, 

 dent. card, utraque valva ii. mimitis, quorum alter bifidus ; v, 

 dext. dent, lat., ant. curto, satis extante, post, nullo ; nymphis 

 Curtis, latis, parum concavis, subito sectis, valvis postea subalatis ; 

 sinu pallii fere cicatr. ant. tenus porrecto. Long. •72. lat, -42. 

 alt. -15. o > , 



Hab. Neeah Bay [Swan)-, Monterey and Cataliua Island, 

 20-60 fathoms, rare [Cooper). 



Subgenus Miodon*. 



Testa Lucinoidea, dentibus cardinalibus, ut in Cardifa, elongatis ; 

 laterali antico parvo instructa. 



This little group of species is intermediate in cliaracter be- 

 tween Astarte, Venericardia, and Lucina. It first appears in 

 the Great Oolite, where it is represented by Astarte [Miodon) 

 orbicularis, J. Sby. Min. Conch, pi. 444. f. 2, 3. This must not 

 be confounded with a second and true Astarte orbicularis, by the 

 same author, pi. 520. f. 2. It appears in Mr. Searles Wood's 

 Crag-series as Astarte curbis. The following is the only receat 

 species at present known. 



9. Miodon prolongatus, 

 M. testa parva, soUda, tumida, compacta, albida ; ventraliter antice 

 valde prolongata, excurvata ; lunula longa, rectiore, haud impressa; 

 umbonibus antice inflectis, obtusis, valde prominentibus ; maro'ine 

 dorsali postico parum excurvato ; costis radiantibus x.-xii. latis, 

 obtusis, marginem attingentibus, parum expressis, dorsaliter obso- 

 letis, a liris incrementi concentricis, plus minusve distantibus, ex- 

 pressis, hie et illic interruptis : intus, margine a costis plus minusve 

 obsoletim crenulato ; cardine dentibus v. dextr., uno postico, inter 

 duas fossas elongato, et lat. ant. lunulari; v.sinistr., dent. ant. trian- 

 gulari, post, valde elongato, lat. ant. minimo, obsoleto; cicatr. add. 

 subrotuudatis, ventraliter sitis. Long. -23, lat. '24, alt. -16. 



Subgenus Adula, Add. (diagn. auct.). 



Testa inter Modiolnm et Lithophagum intermedia, cylindracea ; 

 umbonibus obtusis ; parte antica longiore ; ligamento subinterno, 

 valde elongato ; epidermide haud testacea. 



Animal byssiferum, in cryptis affixum ; muscuHs adductoribus 

 majoribus, antico ovate. 



Constituted by Messrs. Adams for A. soleniformis, D'Orb., 

 which very closely resembles the young of the Vancouver species : 

 enlarged to receive the shells of Lithophagoid shape which are 



* Th. fxfioiv, smsWer ; dSoi'S, tooth. 



236 



