apertures are lateral and subterminal, and which frequently have avicularia and 

 spines. The marsupial chambers are gonocysts or gonoecia. Many of the zooecia 

 may be closed by thin calcareous films«. The author here uses the term »lateral« 

 in quite an unusual way; namely as a synonym to »subterminal«, and when he 

 speaks about »spines« he no doubt means the small projections which in many 

 species are found where three dividing ridges meet each other, and which by other 

 authors have been called »tubercles«. However, he only uses this expression in the family 

 diagnose, and nowhere in the descriptions of the single species. Gregory distin- 

 guishes between gonocysts and gonoecia, and as gonocysts he designates the pyriform 

 greatly enlarged gonozooecia which are provided with a small terminal aperture. 

 He ascribes gonoecia to the genus Nodelea, but in N. durobrivensis he has found a 

 gonocyst, and the gonoecium which he ascribes to N. semihina is really an avicu- 

 larium. To the genus Foricula he ascribes »a gonæcium or gonocyst«, but the piri- 

 form gonæcium (? gonocyst), which he assigns to F. pyrenaica is also an aviculari- 

 um. He is inclined to think that the Eleidae have been provided with chitinous 

 opercula, and the calcareous plates which in so many zooecia cover the aperture 

 he interprètes in the same manner as his predecessors, namely as closure-plates. 



The present author'), in 1902, in a preliminary paper expresses the view that 

 d'Orbigny has been right in ascribing opercula to the Eleidae at the same time 

 pointing out the difference between the operculum and the closure-plate. 



Lang"), in 1906, distinguishes between »closed zooecia and normal zooecia« 

 and uses the presence or absence, the frequence or rarity of the former as a specific 

 character. He says about the closed zooecia: »Like the avicularia their physio- 

 logical significance is a matter of conjecture«. 



The Morphology. 



The Zooecia. 



The zooecia') have essentially the same form and structure as those of the Cy- 

 clostomata being very long slender tubes, each of which rises from the proximal 



nous voyons, mais très-rarement, des cellules difrcrentes des autres, Ijeaucoui) plus jurandes, 

 et que nous rcf^ardons ici comme des cellules ovai-icnnes servant à la reproduction des oeufs 

 (pi. 735, 730, 741, 761, 777). Quelques genres seulement oflVent de veritables vésicules ovariennes 

 distinctes des cellules et placées du côté opposé, deslinées aussi à produire les oeufs (pi. 770). 

 While the cellules ovariennes pictured in pi. 761, 770 and 777 (belonging to Multisparsa Luciana. 

 Hornera lichenoides and lieptomiiUisparsa diluviana) are real cyclostomatous ooecia those figured 

 in pi. 735, 736 and 741 are Eleid avicularia«. To Gregohy, therefore, is due the credit of being 

 the first author who has found gonozoæcia in the Eleidae. 



') IG, p. 28. 2) 19, 



^) In the descriptions of the species the names „zooecia", „heterozooecia" and „kenozooecia" arc used 

 to designate tliat part of the named zooids, which is visible in the surface of the colony. 



