from the Vancouver District, 8 



moored by byssus^ like Modiula. The largest known species ia 

 A. falcata, Gld., which is Dornially straight, but often grows in 

 a twisted burrow. A. parasitica, Desh., and the long-known 

 A. cinnamomea appear congeneric. 



13. Adula stylina. 



A. testa cylindracea, lithopbagoidea, leevi, tenuissima, parum ar- 

 cuata, subnacrea, alitiJa, postice interduni livido tincta ; epider- 

 niide nitente, lajvi, solidiore, nigro-f'nsca : testa jun. typice niodio. 

 Isefornii, umboiiibus subaiiticis, obtusissiuiis ; niargine dorsali 

 antice (rarissinie paululuni, testa minima, postice) teimiter creiiu- 

 lato : testa adulta maigiuibus dors, et veiitr. fere j)aialU'Hs, aiit. 

 et post, rotundatis ; umbonibus detritis, baud conspicuis, circiter 

 sextantim antice sitis ; incrustatione haud solida, densissime spon- 

 giosa, aream posticam diagonalem tegente, supra valvas prolon<;ata, 

 appressa ; lio;amento interne, postice valde prolongate ; pagina 

 interna pallida ; cicatr. add. pestica tumida, pyriformi, antica 

 (quoad familiam) maxima, haud impressa, oblonga ; cicatr. pedali 

 antica magna, circidari, impressa ; callositate subumbonali (testa 

 jun.) cicatr. pedalem versus conspicua. Long. •155, lat. "4, alt. '5. 



Variat t. magis arcuata ; ut \\\ A. falcata, antice tumidiore, sub- 

 angulata. 



Variat quoque testa attenuata. 



Variat interdum ventraliter late hiante. 



Hab. Neeah Bay, abundant {Swan) ; Monterey {Taylor), 



On smashing a large lump of hard clay, bored by Pholads, 

 Petricolids, &c., large numbers of this species, with a few of A. 

 falcata, of all ages from '06 onwards, were tbund in situ. Several 

 struggled for room in a single crypt. The umbos are abraded 

 by the wide opening of the valves. 



14. Axincea (tseptentrionalis, var.) suhobsoleta. 



A. testa A.septentrionali simili, parum insequilaterali, haud tumida; 

 umbonibus obtusis, latis, satis preminentibus ; cinerea, rufo-cas- 

 taneo varie picta ; epidermide cepiosa, sublaminata ; marginibus' 

 ventrali et postice valde rotundatis, antico parum producto, dei- 

 sali recto ; sulcis radiantibus subobsoletis sciilpta, dorsahter ssepe 

 evanidis : intus, margiuibus ventrali valde, ant. et post, parum cre- 

 natis ; lamina cardinis subangulata ; dentibus paucioribus, validis, 

 angustatis ; cicatr. add. antica castanea, callosa ; ligamento su\- 

 cato. Long. -13, lat. -12, alt. '7. 

 Hab. Neeah Bay {Swan) ; Shoalwater Bay {Cooper). 



MiddendorfF's shell is figured with much stronger ribs, buc 

 may have been described from decorticated specimens. 



15. Siphonaria Thersites. 



S. testa parva, tenui, haud elevata, valde insequilaterali, dense nigro- 

 castanea, laevi, seu interdum costulis paucis, obtusis, obsoletis, 



237 



