LACINULARIA SOCIALIS 1 29 



has been so often described that it is needless for me to refer to the 

 subject here. With regard to the teeth, however, what I have seen is 

 considerably at variance with the accounts of both Ehrenberg and 

 Dujardin ; the former calls the teeth of Lacinularia " reihenzahnigen," 

 that is, having a stirrup-like frame, with many teeth set upon it ; and 

 the latter, in his general definition of the " Melicertiens," under which 

 head he places Lacinularia, has " machoires en etrier " (' Hist. Nat. des 

 Infusoires,' p. 6i2).i 



As I have seen it (fig. 6), the armature of the pharyngeal bulb in 

 this species — as in Stephanoceros — is composed of four separate pieces. 

 Two of these (which form the incus of Mr. Gosse) are elongated 

 triangular prisms,^ applied together by their flat inner faces ; the 

 upper faces are rather concave, while the outer faces are convex, and 

 upon these the other two pieces (the mallei of Mr. Gosse) are 

 articulated. These last are elongated — concave internally, convex 

 externally — and present two clear spaces in their interior ; from their 

 inner surface, a thin curved plate projects inwards. At its anterior 

 extremity this plate is brownish, and divided into five or six hard 

 teeth, with slightly enlarged extremities. Posteriorly the divisions 

 become less and less distinct, and the plate takes quite the appearance 

 of the rest of the piece. 



This is essentially the same structure as that of the teeth of 

 iV^£)^o;«;««/«, described by Mr. Dalrymple ('Phil. Trans.,' 1849), and by 

 Mr. Gosse (on the Anatomy oi Notoinmata aurita, Mic. Trans., 185 i), 

 and very different from the true " stirrup-shaped " armature. 



A narrow oesophagus passes directly downwards from the posterior 

 part of the cavity of the pharyngeal bulb, through the neck of 

 the animal to the body, where it opens into the wide alimentary 

 canal. 



This is divided into three portions by an upper, a middle, and a 

 lower constriction. 



The two upper parts are often not very distinctly divided. A 

 wide oval or pyriform sac, whose wall contains many nucleated cells, 

 opens into the upper portion on each side. This is the " pancreatic " 

 sac of Ehrenberg.^ 



The middle dilatation frequently gives origin to several short 

 .cellular coeca. 



The lowest dilatation is globular, and has also several cellular 



"■ Leydig also finds Ehrenberg's figures " untrue to nature." 

 * Not described by Leydig. 



3 According to Leydig there are fiaur of these bodies, two smaller and two larger, and 

 '.they do not open into the alimentary canal. — Loc. cit. p. 463. 



VOL. I K 



