4.24) Dr. P. P. Carpenter on new Forms of Mollusca 
tim eleganter variegata; striis incrementi concentricis, postice ex- 
tantioribus ; umbonibus postice flectentibus, obtusis; parte antica 
prolongata, regulariter excurvata; margimibus dorsali et ventrali 
subparallelis, subrectis ; parte postica curtiore, subangulata: intus, 
dent. card. utraque valva ii. minutis, quorum alter bifidus; v. 
dext. dent. lat., ant. curto, satis extante, post. nullo; nymphis 
curtis, latis, parum concavis, subito seetis, valvis postea subalatis ; 
sinu pallii fere cicatr. aut. tenus porrecto. Long. *72, lat. -42, 
alf. 15. 
Hab. Neeah Bay (Swan); Monterey and Catalina Island, 
20-60 fathoms, rare (Cooper). 
Subgenus Mropon*, 
Testa Lucinoidea, dentibus cardinalibus, ut in Cardita, elongatis ; 
laterali antico parvo instructa. 
This little group of species is intermediate in character 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. pl. 444. f. 2,3. This must not 
be eontamaded with a second and true Astarte orbicularis, by the 
same author, pl. 520. f. 2. It appears in Mr. Searles. Wood’s 
Crag-series as Astarte corbis. The following is the only recent 
species at present known. - 
9. Miodon prolongatus. 
M. testa parva, solida, tumida, compacta, albida; ventraliter antice 
valde prolongata, excurvata ; lunula longa, rectiore, haud impressa ; 
umbonibus antice inflectis, Ghia ale prominentibus ; margine 
dorsali postico parum excurvato; costis radiantibus x.—xii. latis, 
obtusis, marginem attingentibus, parum expressis, dorsaliter obso- 
letis, a liris incrementi concentricis, plus minusye distantibus, ex- 
pressis, hic 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; rs add. 
subrotundatis, ventraliter sitis, Long. *23, lat. °24, alt. ° 
Subgenus Apuxa, Add. (diagn. auct.). 
Testa inter Modiolam et Lithophagum intermedia, cylindracea ; 
umbonibus obtusis; parte antica longiore; ligamento subinterno, 
valde elongato ; epidermide haud testacea. 
Animal byssiferum, in cryptis affixum; musculis adductoribus 
majoribus, antico ovato. 
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. peiwv, smaller; ddovs, tooth. 
