MYTILUS. 



Species 20. (Mas. Cuming.) 



Mytilus bokealis. Myt. lestd oblongo-ovald, .iuharctmtd, 

 temd, tumidiuscttld, lavigatd vel decicssatm striata, 

 antice snbplicatim corrttgatd, umbonibus paulo divari- 

 catis ; nitente olkaceo-nigrd, ad umbones violaced. 



'I'liE NORTHEEN Mytilus. Shell oblong-oviite, somewhat 

 arched, thin, rather swollen, smooth or decussately 

 striated, faintly plicately wrinkled on the anterior 

 side, umboes a little divaricated ; shining olive-black, 

 violet at the umboes. 



L.\M.\RCK, Anim. sans vert. vol. vii. p. 46. 



Hab. Newfoundland. 



A light, oval, swollen shell, of a dark shining olive- 



bhick colour, tinged with violet at the umboes, which are 



somewhat removed from each other. 



Species 31. (Mus. Cuming.) 



Mytilus Chiloensis. Myt. testa oblongd, suhjlabetli- 

 formi, Imvigatd aid minute decussatim airiatd, latere 

 postico recto, aniico suhdepresso, ad ■niarginem rotun- 

 dato-angulato ; luteo-olivaced, versus marginem nitente- 

 olivaced, el obscure radialim lineatd. 



The Chiloe Mytilus. Shell oblong, somewhat fan- 

 shaped, smooth, or minutely decussately striated, 

 posterior side straight, anterior slightly depressed, 

 rotundately angled at the margin; yellowish-olive, 

 towards the margin shining olive, and obscurely ra- 

 diately lineated. 



Philippi, Dunker, MS. in Mus. Cuming. 



Ilab. Island of Chiloe. 



Of rather light substance, of a rich shining olive-colour, 



rayed with fine pencil lines. 



Species 23. (Mus. Cuming.) 

 Mytilus M.\gellanicus. Myt. testa elongato-jnjrifo. 



compressiusadd, versus umbunes urcuatim attenuatti, 

 longitudinaliter radiutim costatd, costis tindato-corru- 

 gatis et crenatis, interdum prope marginem obsolelis ; 

 intense violaceo-uigrd. 

 The Magellan Mytilus. Shell elongately pear-shaped, 

 rather compressed, arched and attenuated towards 

 the umboes, longitudinally radiately ribbed, ribs wave- 

 wrinkled and crenated, sometimes obsolete near the 

 margin ; deep violet- black. 

 Chemnitz, Conch, vol. viii. pi. 8.3, f. 7i3. 

 Hab. Straits of Magellan. 



A very characteristic flattened pear-shaped shell, of a 

 violet-black colour, covered with waved, wrinkle-like, cre- 

 nated ribs. 



Species 33. (Mus. Cuming.) 



Mytilus Pekna. Myt. testa angusto-elongatd, 



cidd, versus umbones gibbd et postice obtuse angulatd, 

 lavigatd vel decussatim striata; violascente, versus 

 marginem intense viridi. 



The Perna Mytilus. Shell narrowly elongated, rather 

 thick, gibbous and posteriorly obtusely angled to- 

 wards the umboes, smooth or decussately striated ; 

 violet, stained with dark green towards the margin. 



Mya Perna, Linnaeus, Syst. Nat. p. 1113. 

 Mytilus elongatus, Chemnitz. 



Hab. Newfoundland. 



Of a narrow elongated form and solid structure, gib- 



bously obtusely angled towards the umboes on the poste- 



Fig. 24. (Mus. Cuming.) 



A fine example in an early stage of growth of Mytilu-^ 

 talus represented at PI. IV. Fig. 12. It is only in this 

 state that a characteristic dark horny band descending 

 posteriorly from the umboes is seen. 



August, 18.57. 



