aS4 MOLLUSCA. CEPHALOPODA. Arethusa. 



depression is observable, and produced by the margin of the last chamber 

 rising on the side of the second. The chambers are rounded externally. 



18. V. suhrotundum. — Mouth depressed, toothless. 



Serpula subrotunda dorso elevato, Walk. Test. IVIin. t. i. f. 4 — ^Ver. sub. 

 Mont. Test. Brit. 521. Flem. Warn. Mem. iv. 565. t. xv. f. 5.— Com- 

 mon. 

 Globular, chambers three, rarely four, inflated and wrinkled. The fourth 

 chamber, when present, seems always unperfectly formed. 



19. V. hlcorne. — The last formed chamber striated longitudi- 

 nally. 



Serpula bicornis ventricosa, Walk. Test. Min. t. i. f. 2 — ^Ver. bicome, 

 Mrnit. Test. Brit. 519. — Sandwich and Reculver, Mr Boyes. 

 Length one Ihie ; chambers three, the middle one small, raised or depres- 

 sed ; tlie last chamber is suboval, compressed, striated longitudinally on the 

 longer side from the aperture ; the other side is smooth : It contracts to- 

 wards the mouth, which is very small and orbicular. 



These species belong to the genus Milista of Lamark, instituted many years 

 subsequent to the Vermiculum of Montagu. The fossil species of France are 

 numerous. 



Gen. VII. ARETHUSA .? {of Montfort). — CeUs arranged 

 obliquely and alternately along an axis, with the mouths 

 of all the chambers having an aspect towards the same 

 pole ; forming a subturriculated shell. 



20. A. lactca. — Chambers ovate, aperture circular. 



Serpula tenuis ovalis Isevis, Walk. Test. Min. t. i. f. 5 — Vermiculum 

 lacteum, Mont. Test. Brit. 522. Flem. Wern. Mem. iv. 566. t. xv. 



f. 6 Among corallines, English and Scotch coasts. 



Length about ^gth of an inch, delicately transparent, with the inner walls 

 of the chambers appearing as white veins. The chambers are six or seven in 

 number, well defined on one side, obscure on the other, contracted towards 

 the mouth. Walker and Montagu obtained this species at Sandwich and 

 Devon, Captain Laskey at Dunbar, and I have it from Leith and Zetland. 



Gen. VIII. LAGENULA.— SheU with a globular body, ha- 

 ving a produced neck or tube. 



* With longitudinal marTcings. 



21. L. striata. — SheU peUucid, with opake,fine, longitudinal 

 striae. 



Serpula (Lagena) striata sulcata rotundata. Walk. Test. Min. t. 1. f. 6. 



Vermiculum striatum, Mont. Test. Brit. 523.— Not uncommon in 



sand on the English shores. 

 In shape, this species resembles a Florence flask ; rounded retraUy ; the 

 mouth is slender and produced, with a small xoiuid aperture ; length not 

 half a line. 



