Vol. 50.] THE INFERIOR OOLITE OP SHIPTON GORGE. 7~> 



bearing few zoeecia, then suddenly increasing in size by rapid multi- 

 plication of zoeecia, until a stoutly piriform head of crowded tubes 

 is formed (PL II. fig. 12). 



Zoeecia small, slightly exsert, tubular, wrinkled: (1) PL III. 

 figs. 5-8, with ovoid mouth, supra-oral ovicell proceeding from the 

 back, pore below the lower lip : (2) compressed, mouth ovately tri- 

 angular, two short processes above, trifoliate opening at the back ; 

 (3) PL III. fig. 10, mouth ovoid, lip arched, apertural plate with a 

 transverse ovoid opening and tubules. 



The ovicell-sacs are globose swellings enveloping several zoeecia. 

 PL III. fig. 8 may represent an early stage of one. It bears a flat 

 top with a perforated disc. 



Pergbksta porifera, sp. nov. (PL II. fig. 6 ; PL IV. figs. 1-5, 

 16, 17.) 



Zoarial length 3-2 mm., zoarial width 1*0 mm. ; zooccial length 

 1*4 mm., zocecial width 0-17 mm. ; mouth 0T mm. 



Zoarium erect, claviform, the axial shaft protruding from the top 

 (PL II. fig. 6). Zoeecia arranged in an irregularly linear series, 

 about six to every annulation, tubular, tapering slightly, exsert for 

 one third of the length. 



Zoeecia: (1) PL IV. fig. 3, central tubular opening, process on 

 each side of the supra-oral rostrum, globular process on the lower 

 lip, mural pore below it : (2) PL IV. figs. 1, 2, compressed, upper 

 and lower lip arched, lower lip with pore below, ovicell supra-oral, 

 springing from the back of the zoeecium : (3) PL IV. fig. 17, young 

 zocecium at the top of the zoarium, with ovoid mouth, trifoliate 

 aperture, and pores around it on the inner wall ; small avicularia on 

 tho lower lip : (4) mural pore orbicular, with cover (PL IV. fig. 5). 



Zoarial surface punctate, with fine intermediate pores. 



One of the doubtful zocecial forms, resembling a columnar avicu- 

 larium (PL IV. fig. 16), appears to have a cover, through which the 

 tubules below can be seen. 



Pergensia porifera is closely related to P. nidulata, but as yet 

 the ovicell-sacs have not been found. 



Pergensia amphoralis, sp. nov. (PL II. fig. 8 ; PL III. figs. 21- 

 24.) 



Zoarial length 4'0 mm., zoarial width 1*0 mm. : month 0"07 mm. 



Zoarium erect, claviform to cylindrical, axial tube protruding at the 

 base and summit (PL II. fig. 8). Zoeecia sub-immersed, or free for 

 half their length, crowded, equidistant, arranged in vertical lines or 

 irregular, about sixteen to a volution. 



Zoeecia: (1) PL III. fig. 21, upper lip arched, ovicell at the back, 

 aperture ovoid, recessed : (2) PL III. fig. 24, compressed, front lip 

 notched, or the wall areolated ; mouth ovoid, with tubules. Front 

 mural pore. 



Zocecial coverings, pitted with the impress of tubules, occur 

 detached on the zoarial surface. Clusters of tubuli are to be seen 

 between the zoeecia in one or two specimens. The ovicell-sacs have 

 not been found. 



