528 MR. A. W. WATEES ON 



to Sderodomus by Levinsen ; B. papillata B. should perhaps be 

 put to UrceoUfora ; B. ahyssicola B. probably belongs to the 

 Cellarinella group ; B. Icevis B. must be placed elsewhere ; B. 

 minuta B. perhaps belongs to the B. reticulata B., B. vagans 

 Thornely, group. 



Loc. Seychelles, 34-39 fath., Aniirante, 34 fath. {Thornely). 

 Wasin, Brit. East Africa (500) ; Ras Osowamembe, Zanzibar 

 Channel (504), collected by Crossland. 



Adeonid^. 



In a short paper in the Annals and Mag. of Nat. Hist, for May 

 1912*, I have given grounds for believing that the Adeonidse 

 will be found to be a much more important group than has 

 generally been supposed, and this in spite of none of the characters 

 upon which it was founded being of the importance then svipposed. 

 A large number of the species are pigmented, most have long 

 pore-tubes, there are triangular avicularia on the front, and 

 often vicarious avicularia on tlie zoarial border, and both kinds 

 are without any cross-bar. There are no external ovicells, 

 the embryos being developed in an ovicellular sac which about 

 half, or, in some cases, nearly wholly fills up the zooecium ; and in 

 a considerable number the zooecium in which the embryo is 

 developed is larger than the others, with a differently shaped 

 aperture, together with a difference in the frontal pores, and these 

 larger zooecia have been called gonoecia. The number of species, 

 however, in which there is no diflference in the ovicelligerous 

 zocecia is very large, perhaps as many are indistinguishable as are 

 externally recognizable. There are no oral glands in any species 

 examined. I had previously shown that in the Adeonella of 

 Busk's ' Challenger' Report there were species in which the pore 

 entered into the zocecial chamber, while in others the pore is 

 above the operculum, also that the opercula in some are nearly 

 straight on the proximal border, others have a broad curve. At 

 the time there was not suiBcient material for complete generalisa- 

 tion, but it is now clear that I was right in separating from 

 Adeonella species with a pore entering into the zooecial chamber, 

 and it is now seen that they also have a more or less sti^aight edge 

 to the operculum. This group is now known as Adeonellopsis of 

 MacGillivray ; and Adeonella, much the same as I restricted it, is 

 accepted. 



The wall of the sac (PI. LXXIII. figs. 3, 5, s.) containing the 

 embryo (figs. 3, 5, emh.) is much thicker than that of the sac in 

 such species as Lepralia cuccidata B., which also has no external 

 ovicells. The very earliest stages of this sac have not been seen, 

 and while it does not ever seem to hang from the opercular 

 region as a small pendant, yet a comparison with the sacs of 



* Ser. 8, vol. ix. p. 493 (1912j. 



