240 FOURTH REPORT — 1834. 



tween the Biliceous spicule found in this genus and in the other 

 Sponges, and the spiculae of oxalate of lime met with in certain 

 plants. In 1828, the Sjiongilla was again made the subject 

 of a memoir, by Dutrochet*. He confirmed Dr. Grant's obser- 

 vations, particularly those relating to the existence of currents 

 (which Dutrochet attributed to endosmose) and the entire ab- 

 sence of Polypi. Dutrochet, however, considered the SpoiigiUa 

 as a vegetable. 



A series of valuable observations relating to the zoophytes 

 were also published in 1828 by Audouin and Edwards f? being 

 a portion of the researches of these indefatigable naturalists at 

 the Chausey Islands. They afford fresh confirmation of the 

 accuracy of Dr. Grant's views respecting the Sponges and Flus- 

 trcE. They also seem to lead to the important discovery that 

 many of the species in this last group possess an organization 

 more complex than has been hitherto supposed, and such as 

 brings them into near affinity with some of the compound As- 

 ciditeX. The same complexity of structure is stated to have 

 been seen by them to a certain extent in many Vorticella;. 

 These observers indeed have found such great differences in the 

 organization of the class of Polypi in general, so far as they 

 have had an opportunity of examining them, that they propose 

 a fresh division of this class into four sections, each of which 

 will constitute a natural family characterized by a peculiar type 

 of structure. ^\iQ first of these groups will embrace the Sponges ; 

 the second, the fixed Polypi, whether naked or incrusted, in 

 which the digestive cavity is in the form of a cul de sachoWovftd 

 out in the very substance of the body {Hydrce, Sertularice, 

 many Vorticellce) ; the third will include those Polypi having 

 a cavity in the body, in the middle of which is suspended a 

 membranaceous digestive canal, communicating outwards by a 

 single opening, and bearing at its lower extremity appendices 

 in the form of small intestines, which appear to perform the 

 office of ovaries {Lohularice, Gorgonicp, PennatulcB, Veretillce, 

 CornularicB, &c.) ; the fourth will include the Flustrcs and 

 other Polypi, in which the digestive canal commvmicates out- 

 wards by two distinct openings, and the organization of which 

 approaches that of the compound ^*c/rf?<^. 



♦ Ann. des Sci. Nat., torn. xv. p. 205. t ^f^t torn. xv. p. 5. 



X Cuvier states that similar observations had been made by Spallanzani, and 

 also more recently by Blainville. He adds, however, that according to Quoy 

 and Gaimard, there are certainly other species in which the animals are true 

 Polypi; and that hence it would be very desirable to ascertain which belong to 

 one type of structure, and which to the other. See Regne Animal, torn. ill. 

 p. ."^OS. note (5). 



