NOETH ITALIAN BETOZOA. 155 



fig. 11; Waters, Quart. Journ. Geol. Soc. vol. xl. (1884) p. 689; 

 ibid. vol. xliii. (1887) p. 342. 



A specimen from Brendola has the zooecial tubes about the same 

 size as the recent and fossil specimens already described, and the 

 ovicell is nearly equal in width and length. 



Log. Living : European Seas. Possil : Crag ; various localities 

 in Australia and New Zealand. 



4. DiASTOPOEA BEENDOLENSIS, Sp. nOV. (PI. III. fig. 1.) 



Zoaria very much compressed, with the zooecia in more or less 

 regular rows. On many of the zooecia there is a tubule, which 

 usually terminates near the zooecial orifice, and runs parallel witi 

 the zooecium, but occasionally it is on the front of the zooecium 

 and terminates near the middle of it. 



These tubules are in a somewhat difierent position from those of 

 the recent Diastopora ohelia, and, as far as I am aware, tubules are 

 known only in these two cases. 



Until this was cleaned with sulphate of soda, I had not seen the 

 tubules and supposed that it was Idmonea compressa^ E,euss (Wien. 

 Tert. p. 46, pi. vi. fig. 32 ; Manzoni, Bri. foss. del Mioc. Austr. ed 

 Ung. p. 6), but in that species no mention is made of tubules. 



There are zooecia on the dorsal surface irregularly placed ; on the 

 front the angular sections of the cells resemble Manzoni's figure 17. 

 Zooecial aperture about 0-06 millim., which is considerably smaller 

 than that of Diastopora ohelia. 



We do not yet understand the function of the tubules, nor do 

 they seem to have received much study, for the only description and 

 figure of their contents is given by Dr. Pergens (Bryozoaires du 

 Cretace, Bull. Soc. Belg. de Geol. vol. iii. p. 311, fig. 4). Some sections 

 that I have cut correspond fairly with Dr. Pergens's description, and 

 upon examination of my sections I was at once struck with the 

 similarity of the ' fibres allonge'es ' to the various muscles in the 

 zooecia ; but in my specimens they form a club-shaped expansion 

 near the extremity of the tubule, and are not arranged in the definite 

 parallel manner figured by Dr. Pergens, being more or less contorted, 

 and a point of considerable interest, not mentioned by that observer, 

 is that the parenchym cord passes through the centre of this bundle 

 of muscles. There are also sometimes muscles lower down attached 

 to the lower part of the parenchym cord, so that this can no doubt 

 be slightly moved by the muscles. 



The internal structure seems to support an idea which I ex- 

 pressed long ago, that these tubules are homologous with the 

 avicularia of the Chilostomata ; by this I mean that the function has 

 originally been the same. In the avicularia there is a parenchym 

 body in a sheath, which can be pushed slightly forward when the 

 beak is open ; and to me this body has always seemed the important 

 part of the avicularium, while, to my thinking, the prehensile theory 

 never rested upon a sufiicient basis. ^ 



^ See my Supplementary Eeport on the ' Challenger ' Polyzoa, p. 27. 



