from the Vancouver District* 8 



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

 A.falcata, Gld., which 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, termissima, parum ar- 

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

 niide nitente, Isevi, solidiore, nigro-fusca : testa jun. typice modio- 

 Jseformi, umbonibus subanticis, obtusissimis ; margine dorsali 

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

 lato : testa adulta marginibus dors, et ventr. fere parallelis, ant. 

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

 sextantim antice sitis ; incrustatione baud solida, densissime spon- 

 giosa, aream posticam diagonalem tegente, supra valvas prolongata, 

 appressa ; ligamento interne, postice valde prolongato ; pagina 

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

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

 antica magna, circulari, impressa ; callositate subumbonali (testa 

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



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

 angulata. 



Tariat quoque testa attenuata. 



Variat interdum ventraliter late hiante. 



Hob. Neeab 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 found in situ. Several 

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

 by the wide opening of the valves. 



14. Axinaa (fseptentrionalis, var.) subobsoleta. 



A. testa A.septentrionali sirnili, parum insequilaterali, baud tumida; 

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

 taneo varie picta ; epidermide copiosa, sublaminata ; marginibus 1 

 ventral! et postico valde rotundatis, antico parum producto, dor- 

 sal! recto ; sulcis radiantibus subobsoletis sculpta, dorsaliter ssepe 

 evanidis : intus, marginibus ventral! 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) ; Shoal water Bay (Cooper). 



Midden dorfFs 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 insequilaterali, dense nigro- 

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



237 



