THE MORPHOLOGY OV THE OHEILOSTOM ATA. 299 



wliicli in other respects gives ii good idea of the genera 

 structure of tlie zooeciuiu, I think lie has put the insertion of 

 the occlusor muscles too near the proximal end of the oper- 

 culum. 



Lepralia dorsiporosa, Busk ^ (fig. 45). 



In one respect this species appears to me to sliow more 

 primitive chai'acters than L. pallasiana. The distal pro- 

 longations (/. sh. d.) of the frontal shield do not completely 

 surround the orifice, the point where they meet being 

 commonly indicated by a slight emai-gination on the distal 

 side of the zooecium. Each distal prolongation typically 

 bears an avicularium (civic). 



'J'lie compensation-sac is seen with great distinctness in a 

 decalcified preparation. It underlies the whole of the frontal 

 wall on the proximal side of the operculum, and it is provided 

 with typical parietal muscles. Tlie distal group on each side 

 is specially strong, and it appears to me that the part of the 

 compensation-sac immediately adjacent to the base of tlie 

 operculum, into which these muscles are inserted, is some- 

 what fascia-like, an arrangement which confirms the view 

 that the muscles function as divaricators. The condyles 

 {cond.) are well-developed recurved hooks. 



Lepralia sincera, Smitt." 



In this species, for specimens of which I am indebted to 

 Dr. Levinsen, the compensation-sac and its muscles resemble 

 those of the preceding species. The distal shoulders of the 

 frontal shield extend no further than about the middle of the 

 operculum. One of these shoulders is occasionally provided 

 with an avicularium. 



Lepralia haddoni, n. sp. (figs. 38, 39). 



Zoarium encrusting or bilaminate (Lscharine). Zooecia in 

 regular longitudinal rows, each about 700 — 900 ^t long and 

 about 370 /t broad. Surface covered by a distinct epitheca, 



' 1884, p. 143. 



3 «01v. k. Vet.-Ak. Forli.,' xxiv (.Biliai.g, 18G7), ISOS, |)|». 28, 177. 



