'24.6 ME. J. W. GREGORY ON THE 



circular in shape. The front wall contains an elongate, depressed areola, the floor of 

 which is cribriform, being perforated by from 4 to 8 pores. A line of punctures runs 

 around the margin of the zocecia. 



Avicularia large, pointing obliquely upwards : situated close below the peristome. 



Gonoecia sparsely scattered, low ; aperture smaller than in the normal zocecia. 



Bistrihution} London Clay : Fareham (abundant) ; Highgate ; Haverstock Hill ; 

 Sydenham ; White Conduit House. 



Figures. PI. XXX. fig. 12. Part of a zoarium from the London Clay, Haverstock 

 Hill, X 3 diam. Fig. 12 h. Several zocecia from the upper part of the same specimen. 

 Fig. 12 c. Zocecia from lower in the same specimen. Fig. 13. Zocecia from base of 

 another specimen. — PI. XXXI. fig. 1. Another specimen. 



Type. Brit. Mus. No. 49756, Edwards Coll. ; Highgate. Wetherell's figured speci- 

 men is B. M. No. B 4443. 



Affinities. Wetherell found a minute fragment of this species in a well at Hampstead, 

 and gave a good but small figure of it ; this, however, seems to have escaped subsequent 

 notice. Mr. Vine first described the species, and he regarded it as a variety of the well- 

 known recent species Adeonellopsis [Beptadeonella, Microporella, &c.) violacea 

 (Johnst.) ; from this, however, it difi"ers very markedly in the nature of the avicularia, 

 the cribriform area, the subtubular peristome, &c. The species to which it is most 

 closely allied is Adeonellopsis distoma (Busk) ; from this the main diff'erence is in the 

 avicularian orifice, which is much smaller in proportion to the size of the peristomial 

 orifice, and it is placed below the latter and not included within the rim, which 

 includes both the avicularium and orifice. In the London Clay species the avicularia 

 are always directed very obliquely upwards. 



Busk has suggested that Eeuss's Eschara coscinophora is synonymous with 

 A. distoma; but agreeing with Mr. Waters [No. 6, p. 283, and No. 13, p. 162], who 

 records the latter from the Italian Upper Eocenes, I prefer to keep them distinct. 

 The London Clay species agree more with A. distoma than yi. coscinophora. The 

 specimens of the latter which agree most with our species are those from the Middle 

 Oligocene of Sollingen in Prussia, figured by Eeuss [No. 7, p. 186, pi. xi. figs. 1-4] : 

 his figure 1 allows of a careful comparison of equivalent zocecia. The differences 

 between the species are that in A. tvetherelli the avicularia are oblique or transverse 

 and much larger, the cribriform plate is larger and has more regular pores, and the 

 secondary aperture is more raised. 



" There seems some confusion as to the localities and horizons of Mr. Vine's types of this species and the 

 next ; the specimen figured as var. h (i. e. fig. 7 6) is recorded as from the Bracklesham Beds of the Isle of 

 Wight ; the slide is, however, correctly labelled from the London Clay. 



