MEDITEEEANEAN AND NEW-ZE A.LAND EETEPOEiE. 257 



by Mr. Earkpatrick asB. sinuosa * differs in several respects from 

 other BeteporcB. The aperture and ovicell resemble those of 

 Lepralia, while there are semicircular avicularia somewhat like 

 those found in B. granulata, B. producta, &c. ; the dorsal surface 

 is vibieated, and the markings on the solid dorsal structure are 

 independent of the zooecia. Although we may feel uncertain as 

 to its ultimate destination, there does not seem sufficient reason 

 at present for removing it from Betepora. 



Another very curious form is mentioned by Mr. Busk f as 

 existing in the Oxford Museum, differing from all known Reteporce 

 in being bilaminate. The opercula and mandibles are said to be 

 exactly the same as those of Betepora tessellata. "Without further 

 examination it would be impossible to say where it should be 

 placed. Mr. Busk proposed for it the name B. escharoides. 



Dr. J. "W. Gregory has proposed a new genus, Scliizorefepora, 

 for those species which have a sinus J, R. tessellata being mentioned 

 as the type, and these in his classification are not only placed in 

 a different family to Betepora but even in another suborder. 

 Careful suggestions regarding classification, like those of Dr. 

 Gregory, are useful as showing the direction in which attempts 

 should be made, and our knowledge of the Bryozoa is yet so 

 imperfect that we need not be surprised when weak points are 

 discovered. If forms showing similarity in so many important 

 zooecial and zoarial characters should have to be placed in two 

 distinct suborders, there would be reason for despairing of ever 

 obtaining a satisfactory classification, and therefore the group 

 called Schizoretepora should receive our careful consideration. 



This group, of which B. tessellata is taken as the type, includes 

 B. Imperati, Busk, B. elongata, Smitt, B. Solanderia, B-isso ; and 

 in all these there is apparently a small sinus, but the opercula of 

 none have any projection on the lower border to fit into a sinus, 

 whereas in Sckizoporella the opercula and aperture correspond. 

 Further examination shows that there are two teeth in the 

 aperture of this group of Betepora, giving the illusive appearance 

 of a sinus. The opercula should, however, whenever it is possible, 

 be examined, as the shape of the aperture may in some cases be 

 misleading, and on this account there is a certain element of 

 uncertainty in the study of fossils. The shape of the opercula, 



* Allied to B. plana, Hincks, Ann. & Mag. Nat. Hist. ser. 6, vol. ii. p. 269. 

 t 'Challenger' Report, vol. xxx. p. 114. 



I " On the British Palaeogene Bryozoa," Trans. Zool. Soc. vol. xiii, p. 224. 



20* 



