HOMOLOGIES. 



55 



a different plan from anything we find in the Tunicata or Polyzoa, but in that of the organi- 

 zation generally, the BracUiopoila possess characters which will scarcely admit of the association 

 of these bivalves with the MollMscou/a* 



* I cannot conclude this divisiou of our subject without referring to a most singular little animal, 

 whose true position is undoubtedly among the AimeUda, but which in many points repeats the polyzoal 

 form so exactly as to render it at first uncertain whether it be not really a hippocrepian Polyzoon that 

 the observer has under his eyes, 



I am indebted to Dr. Wright, of Edinburgh, for an opportunity of examining the little animal in 

 question, of which he obtained two or three specimens from the coast of Devonshire, in May, 1856, and 

 which he preserved alive for some weeks in a vessel of sea-water. Dr. Wright has published an 

 account of it in the 'Edinburgh New Philosophical Journal' for October, 1856, where he describes 

 it under the name of Phoronis hip/jocrejjia. He also kindly placed one of his specimens at my disposal 



Phoi-onis hippocrepia, Wright ; the annelidan honiomorph of the hippocrepian Polvzoa. 

 Fig- 12. Fi-. 13. 



^ 



^U, 





Fig. 13. View in a plane at right angles 

 to that of fig. 12 ; the view of tlie tenta- 

 cuUferous crescent i.s semi-ideal, the 

 tentacula being supposed to be removed 

 from part of its margin, in order to ex- 

 pose the mouth and over-arching lip. 



Fig. 12. Viewed from the side of the oesophagus. 



ua. Tentaculiferous crescent, b. Mouth, e. Lip. .-/. (Esophagus, e. Intestine. /. Vessel conveying the 

 blood backwards from the tentacula and crescentic disc. (jy. The two vessels from whose union the vessel 

 /results, h. Vessel conveying the blood forwards towards the crescentic disc and tentacula. ii. Longi- 

 tudinal muscular fibres in stem. 



