680 ME. A. W. WATERS ON MEMBRAJSTIPOEID^. 



Membranipoea Dumeeilii (And.). 



For synonyms see Hincis, Brit. Mar. Polyz. p. 156 ; and Waters,. 

 "Nortli Italian Bryozoa," Q. Jn. Geol. Soc. vol. xlvii. p. 12, pi. ii. fig. 4. 



Membranipora Dumerilii, Levinsen, Zooloyica JDanica : Mosdyr, p. 57, 

 pi. iv. figs. 22-25. 



In both the Eapallo and British specimens there is often a 

 space between the zooecia, about the size of a zocecium, and it is 

 covered by a membrane in the middle of which there is a slit- 

 like or oval opening; and sometimes zooecia in other respects 

 fully developed have a membranous cover with a similar opening. 

 These curious cells are not confined to the growing borders of a 

 zoarium. 



There are 4 lateral and 1 distal pore-chambers. 



Loc. North Europe ; Britain ; Mediterranean (Eapallo, said to 

 be from 26-30 fathoms, also on Pinna) ; Madeira {J. Y. JolinsorCs 

 collection). Fossil: Pliocene and Miocene of Europe, and the 

 Tertiary of New Zealand. 



Membeanipoea Sophia, BusTc, var. aemifeea, Hinchs. (PL 

 48. fig. 18.) 



Membranipora armifera, HincTcs, Ann, 8f Mag. Nat. Hist. ser. 5, vol. vi. 

 p. 82, pi. xi. fig. 5. 



When I received from Canon Norman a specimen from the 

 Grulf of St. Lawrence named armifera, I at first doubted the 

 determination, as it approached so much more nearly to M. 

 Sop'hi<s than to the specimen described by Mr. Hincks. As a 

 rule there is only one oral avicularium, though sometimes two 

 occur. The spine on the one side is stout, articulate, and trun- 

 cate, whereas that on the other is delicate and acute. The 

 ovicell is raised, globular with a rib, and is surmounted by a large 

 triangular avicularium. There are usually four lateral " pore- 

 chambers " and several distal pores. 



In a specimen oiM. Sophice from the Gulf of St, Lawrence very 

 many of the zooecia, especially the younger ones, are entirely 

 without any trace of spines. 



The M. SojJiice, Busk, is the Reptofiustrina arctica of d'Orb. 

 (Pal. Eranc. p. 582), and is called M. lineata forma Sophice by 

 Smitt, and M. arctica by Lorenz. But d'Orbigny also gave the 

 manuscript name arctica to another northern form, which he 

 called Semijlustrellaria arctica, and this Smitt has described and 

 figured as Membranipora arctica. As d'Orbigny 's description of 

 'Reptofiustrina arctica is very slight and might refer to other 

 species, it will be best to retain for this the name SopMo" of 



