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enumerated the different species of Hydroid zoophytes, hif 

 descriptions being illustrated by large sized diagrams. This 

 portion of the paper we must necessarily omit, as without 

 the illustrations the remarks would not be generally under- 

 stood. The Dr. then proceeded as follows :— " I have now 

 enumerated the various Hydroid zoophytes found on our 

 rocks, and will now turn to the Polyzoa, of which class we 

 have a greater variety here. The tribe of animals we are 

 now about to consider, though practically ranked with the 

 zoophytes, are in reality not zoophytes at all, as a very 

 brief consideration of their organization will shew. They 

 certainly resemble them in outward form, and mode of life, 

 and the dried polypidones of the two can scarcely be dis- 

 tinguished by the unassisted eye ; like the zoophytes wc 

 have been considering, they are composed of a series of 

 horny or stony cells, which are inhabited by animals closely 

 resembling polypes, each with its crown of tentacles, and 

 all united into a compound life. But if we examine them 

 more minutely we shall find they differ completely in 

 all essential characters from the zoophytes proper. I) 33 

 shews a living specimen of one of our shore forms, the trans- 

 parency of whose envelope will allow us to observe the animal 

 within, and the delicacy of its tissues will permit us to pene- 

 trate into the secrets of its internal anatomy. Instead of being 

 a simple sac like the hydra, we see here a complete diges- 

 tive system ; a gullet, two stomachs, and an intestine ; in 

 fact, as highly organised a digestive apparatus as exists in 

 any of tho lower forms of moUusca. And again, the ten- 

 tacles are not here contracted threads, as in tho polypes, 

 but stiff hollow bristles, communicating with the cavity of 

 the body, and permeated by the nutrient fluid ; and beset 

 on both sides by vibratite cilia ; in fact, they are breathing 

 organs, like tho gills of tho oyster or muscle, not instru- 

 ments of prehension, like tho tentacles of the hydra. It is 

 true they also serve to procure the food of tho animal, but 

 it is not by prehension, as the arms of the polypes do, but 

 by ciliary currents, producing a vortex in tho water, in 



