326 Mr. W. Clark on the Animal of Dcntalium Tarentinum. 



branchiae to its terminus, and submitted its substance to micro- 

 scopic powers without discovering a trace of an intestine, which 

 is usually the easiest organ to be detected by its colour and dis- 

 tension. I have carefully watched thirty individuals at a time, 

 and never saw any rejectamenta from the posterior process ; but 

 in the same period frequent discharges anteriorly from the centre 

 of the mantle, of foraminiferous spoil enveloped in mucus. I 

 finally observe, that on the animal being removed from the shell, 

 the medial branchial canal is distended, but in a short time col- 

 lapses from the evaporation of the fluid, and exhibits a deep ca- 

 naliferous groove; and when the canal is not quite full, one or 

 two globules, precisely like those of a spirit-level, may be made 

 with the slightest pressure to float backwards and forwards from 

 the posterior sphincteroid process to the branchiae. Many other 

 circumstances can be added in proof of the posterior entry of the 

 branchial water, but I have already transgressed the limits of 

 conciseness, and it is time to take some notice of the nervous sy- 

 stem, salivary glands, the stomach and its contents, and the sub- 

 stances which fill up the body from the branchiae to the posterior 

 terminus. 



At the base of the oesophagus is a cerebral mass of four mi- 

 nute, pale pink, subcircular, finely-punctured ganglions, in form 

 somewhat like the letter X, united by a nervous thread or collar, 

 which encircles the oesophagus at the point where it passes at the 

 base of the foot into the stomach, and the fine filaments therefrom 

 are distinctly visible passing to the stomach, and throwing off 

 anastomosing lateral threads anteriorly to the foot, buccal orifice, 

 and the other front parts of the body. 



The salivary glands are very large, covering the base of the 

 foot and the oesophageal ganglions, and envelope the buccal 

 pouches so completely that they seem imbedded in them ; they 

 spring from each side the base of the mouth, and are two thick 

 fasciculi, which consist of a multitude of very fine, long, light 

 yellow capillary strands ; their extraordinary volume is necessary 

 to produce a copious supply of fluid to lubricate the enormous 

 quantity of Foraminifera these animals swallow, especially of the 

 scabrous ones, as Bulimina pulchella, and the sharp-pointed La- 

 gena amphora. 



The oesophagus, after emerging from the nervous collar, in- 

 stantly enters the stomachal cavity, which is composed of a mus- 

 cular membrane of a broad oval form, the anterior and larger 

 portion thereof being occupied by an extremely strong gizzard, 

 formed of a pair of subelliptical folding jaws with eighteen laminae 

 bent towards the points on each side, and studded with very 

 strong blunt teeth : this denticular frame is supported by fleshy 

 lobes encased in corneous plates, and appears to be an organ 

 nearly similar to the buccal mass of the ordinary Gasteropoda ; 



