THR MORPHOLOGY OP THE OHEILOSTOMATA, 

 Cases in which the aucestriila is not Tata-like: 



523 



Species. 



Reference. 



Remarks. 



M e 111 b r a n i p r e 1 1 a 

 melolontlia, Busk 



C r i b r i 1 i 11 a a n n ii 1 a t a, 

 Fabr. 



L e p r a 1 i a p a 1 1 a s i a n a, 

 Moll 



L e p r a 1 i a p a 1 1 a s i a ii a, 

 Moll 



Scliizoporella (Hip- 

 po tlioa) liy al iiia,L. 



Scliizoporella (Hip- 

 pothoa) liy alina, L. 



Scliizoporella cris- 



tata, Hiiicks 

 Smit.lia reticulata, 



J. MacGill. 

 Tern a cilia opuleiita, 



JuUien 



Hinck.s ISSO, p. 203 

 Hiiicks, ISSO, p. 194. 

 Hincks, ISSO, p. 29S 



Aperture membranous, but 

 not surrouiideil by spines. 

 Like tiie ordinary zocecia. 



Ijike I he ordinary zooecia. 



Barrois, 1S77, p. 145, Like the ordinary zooecia. 



pi. vii, fiir. 1 I 



Barrois, 1877, p^ 168, Like the ordinary zocecia. 



pi. ix, fi^'s. 9 — 16 

 Jullien, 1888, 4, p. 29, 

 pi. iv, figs. 1 — 4. 



Hincks, 1880, p. 254, 



pi. xl, fi?. 6 a 

 Hincks, 1880, p. 346 



Jullien, 1883, p. 13(sep.), 

 pi. xiv, figs. 26, 29 



Tata-like; resembling the 

 ordinary zooecia; or inter- 

 mediate. 



Litermediate. 



Like the ordinary zooecia. 

 Cribrilina-like. 



There is no othei' form of ancestrula which is known to 

 occur in a number of different types of Cheilostomes, and it 

 is impossible not to agree with Suiitt and others that the 

 view that the primary zooecium shows ancestral characters 

 has much to be said for it. In the majority of described 

 cases the ancestrula is like that shown in fig. 2, and is a 

 typical Membrauipora-like zooecium. In certain forms 

 with an infundibuliform zooecium the ancestrula has already 

 acquired this type. This is the case in Bi cell aria cilia ta, 

 Avhile in Scrupocellaria the ancestrula may show distinct 

 tendencies in the same direction. It is hardly necessary to 

 point out how thoroughly the common occurrence of a Tata- 

 like ancestrula confirms the general conclusions arrived at in 

 this paper. It may be remarked that this type of ancestrula 

 is by no means unlike that of a Cyclostome (which has, 

 however, no spines) ; and these Polyzoa may probably be 

 regarded as forms in which the frontal surface remains 



