228 DENTALIAD^E. 



very minute Foraminifera, a convincing proof of the voracity 

 of these animals. I have never failed to find in them either 

 the Quinque-, Tri-, or Bi-loculinae, or the Rotalia Beccarii, the 

 Lobatula vulgaris, Bulimina pulchella, Textularia oblonga, 

 Lagena amphora, or the Robulina subcultrata, and more rarely 

 a minute bivalve, either the Kellia suborbicularis or Astarte 

 triangularis : this fact is another proof, if any additional ones 

 were necessary, that an animal inhabits the minute calcareous 

 forms which were formerly supposed to enclose Cephalopoda, 

 or to be inserted in their membranes ; they are not inhabit- 

 ants of the littoral, but of the coralline zones, and appear 

 to be the sole aliment of this decided zoophagous mollusc. 

 These shells are in transitu to be acted on by the appendage 

 within the stomach, which will be noticed shortly, and after 

 having undergone its action the rejectamenta are discharged 

 anteriorly with other mucal and faecal matters, and not at the 

 posterior terminus agreeably to M. Deshayes' determination; 

 and I shall presently demonstrate that the posterior aperture 

 is not for anal uses, but to supply the branchiae with water. 



It is now necessary to mention the figure and situation of 

 the heart and branchiae ; these points must be carefully kept 

 in mind, as the demonstration I propose rests on a due consi- 

 deration of them. The heart is a subrotund minute ventricle 

 with a linear depression on its summit, and when opened 

 shows the corresponding ridge ; its surface is fortified with 

 muscular raised lines ; it is fixed centrally at the posterior end 

 of the branchial cavity and base of the stomach, and in some 

 transparent animals may be seen in the pericardium ; in the 

 very young pellucid shells seven inspirations and as many 

 nearly isochronal expirations have been counted in a minute, 

 and the corresponding ingress and egress of the water seen *. 



* Lamarck, in the last edit, of the ' Anim. sans Vert.' (Milne-Edwards's) 

 3rd vol. p. 13, says, " Car, apres les animaux vertebres, la nature n'offre, 

 dans aucun animal, ces mouvements alternatifs et mesures d'inspiration 

 et d'expiration du fluide inspire," &c. 



On this point that great naturalist is in error, as in Dentalium Tarenti- 

 num I have, with a chronometer showing seconds, repeatedly marked nearly 

 isochronal inspirations and expirations of the aerating fluid, the two toge- 

 ther amounting to about sixteen in a minute. 



