Mr. H. D. S. Goodsir on the Development of Acephalocysts. 481 



close both spores and antheridia. In the first the spore, covered 

 with a ciliated membrane, divides into four sporules, as MM. 

 Crouan have already observed ; but, as in the two preceding spe- 

 cies, it is simple in the conceptacle. 



The spores of Fucus canaliculatus present a very remarkable 

 structure : the ciliated membrane which covers them presents very 

 fine and close folds, which disappear soon after the spore has fallen 

 to the bottom of the water, and which allow this membrane to 

 extend and to form around the spores a large transparent margin. 

 These spores divide into two sporules. 



From the preceding observations we think we may draw the 

 following conclusions : — 



That some of the Fuci of our coasts contain dioecious species, 

 and others monoecious. 



That the spores of the Fucacece, however simple they may be 

 in principle, follow in their division the number 2, or one of its 

 multiples. 



That in the present state of science, these characters of fruc- 

 tification being added to those of vegetation, require the esta- 

 blishment of three distinct genera : 



Fucus (F. serratus, vesiculosus, &c.) ; 



Ozothalia vulgaris (F. nodosus) ; 



Pelvetia canaliculata (F. canaliculatus). 



LVIII. — On the Development, Structure and (Economy of the Ace- 

 phalocysts of Authors ; with an account of the Natural Analo- 

 gies of the Entozoa in general. By Harry D. S. Goodsir, 

 Cons. Mus. R.C.S.E .* 



An opportunity having been afforded him by Dr. Gairdner of exami- 

 ning a large mass of hydatids taken after death from the abdomen of 

 a patient who had been long labouring from distension of that cavity, 

 Mr. Goodsir found that they belonged to a new form of Entozoon, 

 which he has called Diskostoma Acephalocystis, the generic term being 

 derived from the peculiar structure of the external membrane cover- 

 ing the vesicles ; for this, examined under a high power, was seen to 

 be intersected by numerous branching tubuli that arose by open 

 mouths from numerous discs of different sizes. These open stomata 

 and tubes appeared to be organs of nutrition. Immediately beneath 

 the above membrane was another of more delicate texture, which sent 

 off very fine septa that traversed and intersected the body of the hy- 

 datid, for the purpose apparently of rendering it support. The mode 

 of generation and development of these animals is very simple. 

 The young hydatids make their appearance as simple cells, gra- 

 dually increasing in size, beneath the internal lining membrane of the 



* Abstracted from the Transactions of the Royal Society of Edinburgh, 

 having been read April 1, 1844. 



Ann.^ Mag. N. Hist. Volxiv. Suppl. 2K 



