M Y T I L U S. 



Plate IV. 



Species 10, (Mus. Cuming.) 

 Mytii.us ekustus, Myt. (eMd oblongo-JlabelUformi, an- 



tice compreasd, longiludinaUter sulcata et bifttrcatim. 



striata, latere postico obtuse aHgulatu ; fused, ockraceo 



srppe radiatd. 

 The scoeched Mytiij's. Shell oblong fan-shaped, 



anteriorly compressed, longitudinally grooved and bi- 



furcately striated, posterior side obtusely angled ; 



brown, often raj'ed with ochre. 

 Lamarck, Anim. sans vert. vol. vii. p. 39. 

 Hab. West Indies. 



A rather compressed, oblong fan-shaped species, strongly 

 longitudinally striated, the strias being here and there bi- 

 furcated, and inclined to pass off in the anterior direction. 

 In colour the shell is mostly of a swarthy-brown, tinged 

 and often rayed with ochre. 



Species 11. (^Ins. Cuming.) 

 Mytilus atkopurpureus. Myt. testa oblongd, tenuiculd, 

 postice tumidd, mx angulatd, longitudinalifer tenui- 

 striatd, striis confertis, 'suhundulatis ; alro-purpwed. 

 The dark-purple Mytilus. Shell oblong, rather thin, 

 posteriorly swollen, scarcely angled, longitudinally 

 finely striated, striai close-set, slightly waved ; black- 

 purple. ^ 

 1)UNKER,_M-S.' in Mus. Cuming. t { ">' >* 

 Hab. Guinea ; Dr. Tams. 



Delicate in substance, verj' closely finely striated through- 

 out, and of a rich dark-purple colour ; collected by Dr. 

 Tams at Guinea. 



Species 12. (Mus. Cuming.) 



Mytilus latus. Myt. testa ehngalo-ovatd, concentrice 

 irregulariter striata, olivaced, sub epidej-mide tenui 

 corned viridi vivide decussatim radiatd; latere postico 

 recto, obtuse declivi, antico arcuato, vix anyulato. 



The broad Mytilus. Shell elongately ovate, concen- 

 trically irregularly striated, olive, decussated with 

 rays of bright-green beneath a thin horny epidermis; 

 posterior side straight, obtusely slanting, anterior 

 arched, scarcely angled. 



Lamarck, Anim. sans vert. vol. vii. f. 4]. 



Hub. New Zealand. 



Of a peculiar straight olilong form, swollen and bluntly 

 sloping on the posterior side, which is straight at the 

 margin, whilst the margin on the anterior side is only 

 slightly angularly curved. 



Species 13. (Mus. Cumiug.) 



Mytilus excisus. Myt. testa oblongo-ovatd, solidiusculd, 

 curvatd, valde gibbosd, longitiidinaliter sulcata et li- 

 ratd, liris confertis, crenidatis, hie illic bifurcatim 

 iJivergentihis, latere postico obtuse coniracto, antico 

 rutundato ; albidd, purpurascente-spadiceo titictd. 



The engraved Mytilus. Shell oblong-ovate, rather 

 solid, curved, very gibbous, longitudinally grooved 

 and ridged, ridges close-set, crenulated, here and 

 there bifurcately diverging, posterior side obtusely 

 contracted, anterior rounded ; whitish, tinged with 

 purple-fawn. 



Tichogonia excisa, Wiegman, Archives, 1837. 



Mytilus fuscus, Kecluz. 



Ffab. Madagascar. 



Of very gibbous solid growth, with the diverging striae 



enlarged into conspicuously crenulated ridges. 



Species 14. (Mus. Cuming.) 

 Mytilus ovalis. Myt. testa oblongo-ovali, plus minus 

 gibbosd, lotigitudinaliter liratd, liris parum crenulatis, 

 undatis, subdistantibua, interstitiis versus marginem 

 lira altera interveniente ; umbonibus tumidiusculis, in- 

 cumbentibus ; nigro-purpured, castaneo tinctd. 

 The oval Mytilus. Shell oblong-oval, more or less 

 gibbous, longitudinally ridged, ridges but little cre- 

 nulated, waved, rather distant, interstices towards 

 the margin with another ridge intervening ; umboes 

 rather swollen, incumbent ; blackish-purple, stained 

 with chestnut. 

 In this species, as Lamarck describes, the umboes are 

 compressly incumbent, presenting a link with the typical 

 growth of the umboes in Modiola. The sculpture con- 

 sists of slightly waved radiating ridges, with au alternate 

 ridge appearing in the interstices as they widen out 

 towards the margin. The colour is blackish-purple, pass- 

 ing beneath the umboes into thestnut. 



August, 185^ 



