ALDIN-GA AXD THE RITER-MTJRKAT CLIFFS, SOUTH ATTSTEALIA. 283 



viously been placed under Microporella, and as many occur fossil 

 from Australia and other f)laces, it becomes necessary to give especial 

 attention to this new genus. It would certainly seem that a number 

 thus placed have marked characteristics, which make it advisable to 

 separate them ; but Mr. Busk has certainly overlooked important 

 points, which make it necessary to reduce his list very largely ; for 

 some have a median pore entering into the zooecial cell, while others 

 have a pore or opening above the opercular aperture, and every one, 

 whatever his ideas of classification, will admit that this is a most 

 important distinction, placing them in different families in spite 

 of a certain similarity in general appearance. The importance of 

 noticing the position of the median pore or opening I pointed out 

 (Quart. Journ. Geol. Soc. vol. xxxviii. p. 269) when considering 

 Porina larvalis^ jVIacGr., and this distinction is recognized by Mr. 

 Busk when creating the genus Haswellia. My own collection is not 

 very rich in these groups, but nevertheless is ample to study them. 

 AdeoneUa platalea, Busk, for which I am indebted to Mr. Haswell, 

 who sent it over as Eschara hecvagonalis, is a most characteristic 

 AdeoneUa, with oral operculum and avicularian mandible correspond- 

 ing with Mr. Busk's figure, and here the pore enters into the peri- 

 stome just above the operculum, which is placed very low down. 

 AdeoneUa j^ohjstonieUa, Ess. (^Eschara Pallasii, Heller), living near 

 Naples and elsewhere in the Mediterranean, and fossil from the 

 Miocene and Pliocene, has the characteristic operculum of the 

 AdeoneUa group, and the central pore opens above the oral aperture, 

 so that when a young cell is examined, there is no pore, but one is 

 afterwards formed by the growth of the peristome which at an early 

 stage bridges over the front, just as figured by Mr. Busk in Smittia 

 jacohensis (pi. xix. fig. 7). The oral aperture of AdeoneUa poly- 

 stomeUa has a sinus which is seen through the central pore. Micro- 

 poreUa violacea, Johnst., which Mr. Busk would now include in a 

 genus ReptadeoneUa, has a true median pore which enters into the 

 zooecial cavity, and is formed when the zooecium is in an early 

 stage. It also has an operculum with a straight edge, similar to 

 that of MicroporeUa ciUata, &c. 



From Mr. Busk's figures and from specimens collected near Capri, 

 it is clear that MicroporeUa distoma is not an AdeoneUa, nor is 3L 

 coscinopora, E.ss., which is distinct from J/, distoma. M. Uchenoides, 

 M.-Edw., and M. fissa, Hincks, have also the median pores opening 

 into the zooecial cavity, and must at present be united with Micro- 

 poreUa., though possibly they may some day be placed in a separate 

 genus. This leaves us with AdeoneUa polymorplia, B. ; A. platalea, 

 B. ; A. intricaria, B. ; A. atlantica, B. ; A. pectinata, B. ; A. poly - 

 stomella, Ess. 



Seeing that the median pore of the Microporellidaj, and the central 

 pore of AdeoneUa are structurally different, and that the oral aperture 

 and operculum in the two families have different shapes, we feel sure 

 that it merely requires this to be pointed out for Mr. Busk and 

 every one else to see that they cannot be placed in the same genus ; 

 for it would be going back in classification if we were to be misled 



