no MOLT.USCA. 



li'uits, and the animal, like that of a Teredo, has two small valves, 

 and as many palettes. Recent specimens are only obtained from 

 the Indian Ocean, but they are found fossil in Europe*. We should 

 approximate to them the 



Gastroch^na, Spengler. 



Where the shells are deprived of teeth, and their edges being vs^ide 

 apart anteriorly, leave a large oblique opening opposite to which 

 there is a small hole in the mantle for a passage of the foot. The 

 double tube, which can be retracted completely within the shell, is 

 susceptible of being gx'eatly elongated. It appears that they are cer- 

 tainly furnished with a calcareous tube f . 



In some of them, as in the Mytili, the summits are at the anterior 

 angle J; in others they are placed near the middle §. 



They inhabit the interior of Madrepores, which they perforate. 



Two genera of Acephala furnished with tubes, have been detected 

 among fossils, but the first of them, the 



Teredina, Lam., 



Has a little cuilleron on the inside of each of its valves, and a small, 

 free, shield-shaped piece on the hinge J|. In the second, 



Clavagella, Lam., 



One of the valves is clasped bv the tube, leaving the other, however, 

 free^. 



A single living species is found in the Madrepores of the 

 Sicilian seas, which has been described by M. Audouin. 



Some naturalists think we should also place in this family 

 the 



AsPERGILLUM, Lam., 



The shell of which is formed of an elongated conical tube, closed at 

 its widest extremity by a disk perforated with numerous small tu- 

 bular holes ; the little tubes of the outer range being longest, form a 

 kind of corolla round it. The reason for approximating them to 



* Teredoclava, Gmel., Spengl., Naturfosch., XIII, 1 and 2, copied Encyc. Method., 

 Vers., pi. clxvii, f. 6 — 16. It is the Fistidana gregata, Lam.; — Teredo utricuhts, 

 Gm., Naturf., X, i, 10; probably the same as the Fistidana lagenula, Lam., Encyc. 

 Method., I, c, f. 23 ; — Fistulanu clava, Lam., lb., 17, 22. 



It is probable that the Pholus tereihda, Pall., Nov. Act. Petrop., II, vi, 25 is also 

 a Fistnlana. 



-f- This tube has been observed by Messrs. Turton, Deshayes, and Audouin. 



+ Pholas Mans, Chemn. X, clxxii, 1678, 1679. 



§ Id., 1661, a very different species from the preceding, not properly distinguished 

 by Chemnitz. 



II Teredina personata. Lam., and Desh., Foss. de Par. I, pi. i, f. 23, 28. 



^ CI. echinata, Lam., Ann. duMus., XII, xlii, 19, CI. coronata, Desh., Foss., I, v. 

 15, 16. 



