OVICELLS OF OVCLOSTOMATOUS BETOZOA. 



275 



Oil some Ovicells of Cyclostomaious Bryozoa. 

 By Arthur Wm. Waters, F.L.S., Y.G.S. 



[Read 5th April, 1888.] 

 (Plate XIV.) 



For the determination of the Cyelostomatous Bryozoa the ovi- 

 cells are certainly most important characters, and in many cases 

 are undoubtedly of generic value ; but how far this is universally 

 the case we are not yet in a position to decide. It may, how- 

 ever, safely be said that the Cyclostomata will never be rescued 

 from their present confusion until we are more fully acquainted 

 with these receptacles. Though of such paramount importance, 

 they are not known in a large majority of species. This is partly 

 on account of insufficient search, but more from the fact that 

 large numbers of specimens are often found without any ovi- 

 cells ; so that in some common species they are as yet unknown. 

 For instance, Hornera concatennata^ E;euas, a fossil found abun- 

 dantly in the Mioceue of Italy, G-ermany, Austria, and Hungary, 

 has, so far as we know, never furnished an ovicell. 



It will thus be seen that with the Cyclostomata it is often the 

 case that abundant material is necessary for true appreciation of 

 the characters, and therefore it was a considerable disappoint- 

 ment that the results of the ' Challenger ' Expedition were not 

 richer in this respect. lam, however, now able to add figures of 

 the ovicells of three species found by the ' Challenger,' one from 

 ' Challenger' material, and two from specimens in my own collec- 

 tion from other localities. 



Hornera fissurata, Busk. (PL XIV. figs. 1, 3, 4, 7 ) 

 Taking them in order : when, through the kindness of Mr. John 

 Murray, I received two colonies oV^Idmojiea jissurata,"" Busk, from 

 ' Challenger' "Station 320," near Monte Video, I was surprised 

 to find a dorsal ovicell upon one, giving sufficient ground for 

 removing it to Hornera; but the structure of both the front and 

 back would have led me to do this independently of the ovicell. 



As Miss Busk had kindly sorted and forwarded the specimens, 

 I informed her what I had found ; and she replied that she had 

 also noticed them, and mounted some for the British Museum, 

 and added that it v\ as to be regretted that " there did not happen 

 to be any among the rather numerous specimens selected for 



LINN. JOURN. zoology, VOL. XX. 22 



