8 



:mk. a. w. waters on 



There are oul}* small fragments of this, which are without 

 ovicells or avicularia, so that it is difficult to say which are its 

 nearest allies ; and in the absence of these characters there is 

 nothing to distinguish it from C. hicornis, B., and C. tenuirostris, 

 B.j or C. ovicellosa, W. 



At first Eeuss united it with C. JistuJosa ; but he afterwards saw 

 that they were distinct. Manzoni, however, subsequently con- 

 sidered them synonymous ; but in this I cannot agree. 



Log. Yal di Lonte and Montecchio Maggiore {Bss.) ; Miocene of 

 Vienna (Rss.) : Brendola ; Crosaro. 



Onychocella. 



Several attempts have been made to group the Membraniporas 

 into fresh genera, but there has been very little success, as divisions 

 have so often been based, not on fresh characters, but only on 

 variation in degree of common ones — as, for instance, the sloping 

 inwards of the wall of the area, though no doubt fresh characters 

 will ultimately be found permitting of a division of the genus. 



There is, however, one section which may be separated, even 

 though the limits scarcely admit of exact definition at present. It 

 is only represented by two or three * living species ; but was 

 extremely abundant in Cretaceous times. Jullien t first attempted 

 separation, based upon the nature of the large vicarious avicularia, 

 of which the mandible is attached to the membranous cover, and 

 there is no bar across the calcareous avicularian opening ; also, 

 as I have pointed out t, there are free chitinous appendages at each 

 side of the base of the mandible. The avicularian opening is, there- 

 fore, simple, and usually oval, or nearly round, and the mandibles, 

 as far as known, are winged, and this also obtains in Membrani- 

 jjora permunita, Micropora lejnda, H., and Foveolaria falcifera^ B. 



Jullien established a family, of which the generic divisions were 

 based principally upon the outline shape of the zoarium, and partly 

 upon the shape of the opesia ; but these are very uncertain cha- 

 racters for generic divisions, as may be seen from my figure of 

 the recent Memhranipora angidosa §, and also in fossil specimens. 

 On this account, I am quite unable to follow Jullien with regard 

 to the other genera into which he divides his family, and only 

 accept the genus Onychocella. Besides the points to which Jullien 

 drew attention, I would add that in Onycliocella angulosa there are 

 trabeculae bordering the operculum. This is general in Cellaria, as 

 pointed out by Mr. Busk ; and I have shown that it also occurs in 

 Selenaria macidata || ; but when we go back to the Chalk we have 

 in Escharella argus, d'Orb., a form which shows in a somewhat unex- 

 pected way the connection between Onychocella and Cellaria ; for, in 

 a specimen which I collected from Maastricht, there are teeth in the 



* Memhranipora angulosa, E,ss., and Melicerita duhia, Busk. 



t " Nouv. Div. des Bryoz. CheiL," Bull. Soc. Zool. France, vol. vi. 1881. 



X Journ. R. Microsc. Soc. ser. 2, vol. v. p. 106, fig. 42. 



§ Ann. Mag. Nat. Hist. ser. 5, vol. iii. pi. xiii. fig. 3. 



il Suppl. ' Challenger ' Report, p. 37. 



