G. E. VINE ON THE FAMILY DIASTOPOEIDJE. 



387 



Busk's D. obelia. D. oolitica is a very characteristic type, especially 

 of the Pea-Grit Series, in the Cheltenham district at least. 



Another type, not the least important of the whole group, is a 

 most peculiar one. In general habit and mode of growth it seems 

 to be a true Diastopora ; but it must be looked upon more as a pas- 

 sage form than as a constant one in all its characters. The t} T pe of the 

 cells, when slightly worn, approaches nearer to that of the Palaeozoic 

 Ceramoporce than to any Mesozoic Diastoporce; but in the more perfect 

 cell the largely developed peristome is unlike any thing in the more 

 ancient or the more recent Diastoporidse. If this be a true passage- 

 form, rather than a constant one, the tendency is toward the Pus- 

 tulopora-subverticellata type*. In this type the cells are connate; 

 but in the one under consideration only some few of the cells are 

 connate ; the great majority are " separated pores," as in ordinary 

 Diastoporce. My diagnosis is made from both the younger and older 

 growths of several colonies • and the description may be relied upon, 

 however the species may be placed in the future. In the Pea-Grit 

 Series the cells have a very bold outline, with interspaces (in some 

 places) between cell and cell. In one specimen from Chipping 

 Norton the cells have a Lepralia-hke growth, the colonies being 

 semicircular and piled one upon another ; and some of the cells are 

 so immersed that only the peristome can be seen. In naming this 

 " type " or " species," I desire to preserve a generic name, though 

 the genus itself is now merged in that of Entalophora and Spi- 

 ropora. 



4. Diastopoea ceicopoea, mihi. Plate XIX. figs. 18-25. 



Zoarium adnate, forming small and large irregular patches, some- 

 times self-attached, at other times incrusting other species of 

 Polyzoa. In the early stages of growth the colony has a bicircular 

 or oval outline; in its later stages the growth is most irregular. 

 Zooecia short and stunted tubes, very coarsely punctate ; orifice 

 ring-like, with a largely developed peristome. Primary zocecium 

 inconspicuous, being deeply immersed, giving off to the right and 

 left secondary zooecia, which in their turn give off others. >The 

 after colonial growth is thus early directed to two opposite points ; 

 ultimately the proximal cells unite below the primary cell, so that 

 it in time becomes centric or excentric. Ocecia ? 



Range from Pea-Grit to Great Oolite. 



Cabinets : several very fine specimens of this type are in the cases 

 of the Museum of Practical Geology, Jermyn Street ; Mr. Longe's, 

 Mr. Walford's, and Mr. Windus's. 



Hab. Chiefly on water-worn stones and broken shells. 



I have had very great difficulty in describing this type, more 

 particularly on account of its peculiar preservation. One colony on 

 Mr. Longe's specimens (block 6) is very well preserved in its earliest 

 stages ; and from this specimen most of the figures are drawn. The 

 natural size is shown at fig. 18, and is about three lines at its widest 



* See Busk's ' Crag Polyzoa,' pi. xviii. fig. 1, right-hand specimen. 



