320 Scientific Proceedings, Royal Dublin Society. 



these structures are only found in the enclocoeles (intraseptal 

 spaces) in both species. 



The points in which Bunodes thalUa resembles Tealia bunodi- 

 formis are the following : (1) the possession of " endodermal 

 saccules ; " (2) the form and arrangement of the mesenteries ; 

 and (3) the nature of circular muscle. 



In order to ascertain, if possible, whether these characteristics 

 should be looked upon as affording generic or specific distinctions, 

 we were led to examine the two native forms which externall}*', at 

 least, present the greatest similarity to Bunodes thattia ; these are 

 Bunodes verrucosa, and Tealia crassicornis. 



Tealia crassicornis. 



We have examined several living specimens of this well known 

 form. We found that the arrangement of tentacles given by 

 Grosse, viz., 5, 5, 10, 20, etc., is invariably present. Though the 

 warts usually appear as irregularly scattered over the surface, they 

 are really arranged in vertical rows between every alternate pair 

 of lines of the insertions of the mesenteries 1 . This is most easily 

 seen to be the case in young specimens, as they expand equally 

 with greater readiness. We cut transversely two young specimens 

 in which we had previously ascertained the arrangement of 

 tentacles and warts to be as above stated, and we found the 

 arrangement of mesenteries to be as follows : — 



There are two pairs of directive mesenteries attached to the 

 oesophagus throughout its entire length, even to those portions of 

 it which form the lappets, and project below the rest of the oeso- 

 phagus. The oesophageal grooves are strongly marked, and 

 correspond to the directive mesenteries. At either side between 

 the directive mesenteries are four other primary pairs, all perfect, 

 that is, reaching the oesophagus throughout its entire length. In- 

 tercalated between these are a secondary series of ten pairs, which 

 reach the oesophagus in the region of the oral disk, but not below. 

 Then there comes a tertiary series, consisting of twenty pairs, 



1 Agassiz (Conrptes rendus T. xxv. p. 678) has described a pentamerous arrange- 

 ment of parts in Actinia {Mhodactinia) davisii, a species since shown to be identical 

 with T. crassicornis. 



