from the Vancouver District. 8 



moored by byssus, like Modiola. The largest known species ia 

 A.falcata, Gld., whicb is normally 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, lithophagoidea, Isevi, tenuissima, parura ar- 

 cuata, subnacrea, albida, postice interdum liyido tincta ; epider- 

 niide nitente, Isevi, solidiore, nigro-fusca : testa jun. tvpice medio- 

 Jseformi, umbonibus subanticis, obtusissimis ; margine dorsali 

 antice (rarissime paululum, testa minima, postice) tenuiter crenu- 

 lato : testa adulta margiiiibus dors, et ventr. fere parallelis, atit. 

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

 sextantim antice sitis ; incrustatione baud solida, densissirae spon- 

 giosa, aream posticam diagonalem tegente, supra valvas prolongata, 

 appressa; ligamento interno, postice valde prolongato ; pagina 

 interna pallida ; cicatr. add. postica tumida, pyriformi, autica 

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

 antica magna, circulari, impressa ; callositate subumbonali (testa 

 jun.) cicatr. pedalem versus conspicua. Long. '1.55, lat. '4, alt. '5. 



Tariat t. magis arcuata ; ut in A. falcata, antice tumidiore, sub- 

 angulata. 



Tariat quoque testa attenuata. , 



Variat interdum ventraliter late biante. 



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

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



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



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



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



by the wide opening of the valves. 



14. Axineea [Iseptentrionalis, var.) subobsoleta. 



A. testa A. septentrionati simili, parum insequilaterali, baud tumida; 

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

 taneo varie picta ; epidermide copiosa, sublaminata; marginibus' 

 ventrali et postico valde rotundatis, antico parum producto, doi- 

 sab recto ; sulcis radiantibus subobsoletis sculpta, dorsaliter ssepe 

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

 natis ; lamina cardinis subangulata ; dentibus paucioribus, validis, 

 angustatis ; cicatr. add. antica castauea, callosa ; ligamento sn\- 

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

 Hab. Neeah Bay (Swan); Shoalwater Bay [Cooper). 



Middendorff s shell is figured with much stronger ribs, but 

 may have been described from decorticated specimens. 



15. Siphonaria Thersites. 

 S. testa parva, tenui, baud elevata, valde inEequilaterali, dense nigro- 

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



237 



