PECTUNCULUS.— Plate IX. 



The general outline of this fine species is exactly the 

 same as that of a worn discoloured shell figured in 

 Chenu's ' Recueil de Coquilles ' in illustration of the 

 Pectunculus undulatus of Lamarck, a species which I 

 cannot identify ; its detail of character is however quite 

 at variance with the description. "The longitudinal 

 grooves of the P. undulatus," says Lamarck, "are very 

 apparent," whilst this shell, which is in the finest pos- 

 sible condition, cannot be said to be grooved at all, the 

 elevated rays are so superficial. There is also no indi- 

 cation of any waved spots on the body of the shell, nor 

 of any streaks on either side of the ligamentary area ; 

 the rays are moreover characterized by a particular style 

 of grey livid painting, which is unquestionably of great 

 specific importance. 



Species 52. (Mus. Cuming.) 



Pectunculus Delessertii. Pect. testa orbiculari, tumi- 

 diusculd, subsolidd, inccquilaterali, altitudine longi- 

 tudinem icquante ; radiatim sulcata, sulcis numerosis, 

 profundis, subtilissime striatis, liris intermediis sub-- 

 tilissimegranuloso-corrugatis, longitudinal iter incisis ; 

 albd, fasciis pluribus aurantio-brunneis transversim 

 undatd, intervallisfusco lineato-punctatis ; intus albd, 

 antice rubido-purpureo tinctd. 



Delessert's Pectunculus. Shell orbicular, somewhat 

 swollen, rather solid, inequilateral, height equal to 

 length ; radiately grooved, grooves numerous, deep, 

 and very finely striated, intermediate ridges very 

 finely granulously wrinkled, and longitudinally cut 

 or engraved ; white, transversely painted with se- 

 veral waved orange-brown bands, the spaces be- 



tween which are punctured with short lines an 

 dots of the same colour ; interior white, stained an 

 teriorly with light reddish purple. 



Reeve, Pro. Zool. Soc, 1843. 



Hab. ? 



I have named this beautiful shell, at the desire of Mi 

 Cuming, after the very highly-respected individual t 

 whom he is indebted for it ; though it is not withou 

 feeling some degree of compunction that the peculiari 

 ties above-noted may be merely certain modified condi 

 tions of the Pectunculus assimilis. It is true that th> 

 shell is rounder and more swollen, and consequently 

 without that angular attenuation which throws the um 

 bones into an oblique direction and contracts the liga 

 mentary area in the P. assimilis ; there are naoreove 

 nine or ten well- developed ridges in the shell unde: 

 consideration, whilst in that under comparison then 

 are not more than five or six, and the internal mar<ri 

 nal denticulations are consequently narrower and mors 

 numerous. Future discoveries can alone decide whethei 

 these are constant differences or casual modifications. 



Species 19. (Fig. 19 b, Mus. Cuming.) 

 (Second notice.) 

 Pectunculus roseus. 



It is with much satisfaction I am enabled to confirm 

 the value of a new species introduced in Plate IV. under 

 the above title, and which I thought might possibly be 

 the young of the P. laticostatus. The specimen here 

 represented is a fine adult example of the small odd 

 valve figured at PI. IV. fig. 19. I do not see any cha- 

 racter to add to those given in the description. 



