272 



each hearing two rows of zo<»'i'ia, with Ihoir hasal siirlaccs towards each 

 other. 



Stat. 1G3 A, Challenger (British Musenm). 



Euthyris obtecta Hi neks. 

 Annals Nat. Hist., Ser. fi, Vol. X, IS.S'i, pag. !)6, IM. 1(1, iigs. ;!2— ;57. 

 Harnier, Qnarl. Jonrn. Micr. Science, n. s. Vol. 4(5, \W,\, i)ag. 277, PI. 1"), 



tigs. 13—14. 

 (PI. \V, fig. 2a-2l). 



The zooecia are slighlly calcilied, arched, I'roni a narrow proximal end ex- 

 panding dislally, with a distal end ohliquely a.scending towards the frontal cover- 

 ing menihrane. When seen from the frontal surface they seem to he cylindrically 

 oval, while from the hasal surface of the colony they are of a lyre-shaped out- 

 line. The strongly projecting covering memhrane is directly connected with 

 the separate zowcia only in the periphery of the aperture of the latter, and he- 

 sides only in contact with them through rod-shaped or ridge-like processes 

 from their surface. The aperture is provided with two well-developed, rounded 

 hinge-teeth. Its anter is semi-circular and rather high and its j)oster ahont half 

 as high, hi the latter we may more or less dislinclly distinguish hctween two 

 proximall}' converging lateral portions and a central j)ortion. The accessory part 

 of the operculum has a wcll-chilini/.cd margin, on either side of which Iherc is 

 a small, tubercle-shaped process corresponding to a small, rounded indentation 

 on the proximal side of each hinge-tooth, hi the somewhat neck-shaped i)art of 

 the zofficiuni proximally to the aperture we find a circle of 8 — 10 superficial, 

 uniporous rosette-plates and a larger number (15—2(1) are scattered over the 

 entire basal surface. There are further numerous, uniporous rosette-plates in the 

 basal pari of the distal wall, and a zig/ag row of about S such plales in the dis- 

 tal half of each lateral wall. 



The connection between Ihe projecting covering nuMubrane and llie cryptocyst 

 is brought about, as far as the frontal and basal surfaces are concerned, by 

 means of a numlier of thin, compressed, almost filiform calcareous prolongations, 

 which join the covering membrane with a T-shaped terminal part. The.se struc- 

 tures appear on the frontal surface only on the two outer series of marginal zoa-cia 

 on either side, and on the series next to the outermosi one they only appear in a 

 number of 2 — 3 a little proximally to the aperture and near the outer margin. 

 In the distal half of the marginal zoeecia they are present in a larger number 

 of about 4 — 7. On the i)asal surface they are found in all zod'cia in a number 

 of 4 — 12. On the middle row of zoiecia we find the distal half of each zod-cinm 



