Mr. W. Clark on the Muricidae. 129 



heavy, strong, ridged, undated varicose typical Murex undatus. 

 The series I speak of are the identical shells of Professor William 

 King vs^hich have passed into my hands, and were the illustra- 

 tions of his valuable malacological paper in the 18th volume, 

 p. 248, of the ' Annals of Natural History,' the perusal of which 

 1 earnestly recommend to naturalists, as he has therein de- 

 monstrated that in this species the singular and great de\dations 

 of form, as the slenderness, tumidity, markings, &c., do not arise 

 from generic distinction, but from the influences of climate, ha- 

 bitat, food, and bathymetrical considerations. 



If these views are valid, they explode the long-held opinions 

 that external form and markings ought to be regarded as uner- 

 ring elements of generic distinction ; and our observations appear 

 sufficiently to prove that this doctrine has too long been insisted 

 on, even in animals of essentially similar structure, both of the 

 external soft parts and internal anatomy. 



I am. Gentlemen, your most obedient servant, 



William Clark. 



On a new species of Chemnitzia. 



Bath, l/th January 1851. 



Postscript. — My friend Mr. Barlee, whose persevering labours 

 in this branch of zoology have often been very favourably men- 

 tioned in our ' Annals,' presented me some time ago with a mi- 

 nute shell, which he considered an unpublished Rissoa, but on 

 examination I found it had all the conchological characters of a 

 Chemnitzia. Mr. Barlee obtained it in the Shetland Islands. 

 That the honours due to him may not be taken up by some 

 Bathyllus, I send the specific characters, and request the favour 

 of their insertion in the ' Annals.' 



Chemnitzia Barleei (n. s.). 



C. testa gracili, alba, costis circa duodecim subrectis instructa ; 

 anfractibus quatuor rotundatis, quorum primus, in sequentem 

 reflexus, alter, duabus, tertius, et ultimus, striis tribus spiraliter 

 cincti. Apertura subovalis, baud continua, labium columuare 

 plica obsoleta, vel penitus abdita, latus externum, sine callo. 

 Sutura linearis, distincta. Umbilicus vix notatus. Axis -^-^, 

 diameter -^^ uncise. 



Hab. ad insulas Zetlandicas. 



These characters indicate, as far as conchological ones can, that 

 [.the animal when observed will prove a Chemnitzia. The outer lip 

 is without the callus of most of the Rissoce ; the apex is undoubt- 

 edly reflexed, a character which is generally the concomitant of 



Ann. ^ Mag. N. Hist. Ser. 2. Vol.V\\. 9 



