BRYOZOA 61 



it is Chalostomata, and sections of the organic parts hâve a close resemblance to those of 

 Bifaxaria denticulata Busk (see PI. VIII, fig. 18). On the dorsal surface there are irregular 

 élévations, no doubt corresponding with the position of the zoœcia. 



There are no avicularia in the two small spécimens, nor are there polypides, the zoœcia 

 being empty, so that but little can be said about the generic position but it is in no way 

 related to Retepom. It is however closely allied to Reteporella myriozoides Busk ('), though 

 examination of the British Muséum spécimens shows, that they should be specifically separated 

 while belonging to the same genus. 



Habitat. — Falkland Islands « dans le sable de fond » (d'Orb.). 



Exp. Antarct. Belge. 



N° 348, Tangles IV. Lat. 71 18' S.- Long. 8S Ù 02' W. ; 435 met. ; — o.3 C. 



N° 428, Tangles VI. Lat. 71" 19' S.- Long. 87° 3;' W. ; 436 met. ; — 0.2 C. 



SMITTIA 



From the Antarctic there are many species with a central lyrula, which at présent 

 we must place under Smittia, although recognising that, as more characters are studied, this 

 group of forms with a suboral denticle will hâve to be divided into several divisions, and we 

 are not yet clear as to the classificatoiy value of the lyrula, which supports the operculum. 

 The cardellae or latéral denticles are not of as much value, and latéral denticles occur in a 

 large number of gênera though sometimes they are but small. According to Hixcks the cardinal 

 character ofthis genus is the elevated secondary orifice, produced and channelled in front. 

 With this view I cannot agrée, and various authors hâve called attention to the peristomial 

 characters being unsatisfactory. The lower edge of the operculum is straight, or slightly 

 curved inwards, the muscular attachments are usually a ridge on the border and as a rule, but 

 not universally, the operculum is very thin, and is not so easily studied as in most gênera. 



Julliex, who attached so much importance to surface structure, accepted this genus, 

 containing species in which the surface is perforated ail over, others with the pores round 

 the border, and again others which seem to be imperforate. The characters upon which he 

 bases the genus and the family are the lyrula and cardella within the aperture. Thèse are 

 characters interdépendant upon the operculum which closes the oral aperture, and while they 

 require further study I accept them as of classificatory value. As Jullien considered that 

 too much value had been attached to the aperture, he does not hère seem quite consistent. 



Porella, which is but a section of the Smittidœ, is well represented in the Arctic but not 

 in the Antarctic. 



Smittia marsupium (MacGillivray) 



fPl. IV, fig. 4) 



Lepralia marsupium MacGillivray, Trans. Roy. Soc. Vict., vol. IX, p. i36 : Zoo!, of Victoria, dec. IV, p. 22. 



pi. XXXV, fig. 4 : BrsK, Zool. Chall. Exp., pt. XXX. p. 147. fig. 44. 

 Porella marsupium MacGillivray, Proc. Roy. Soc. Vict., vol. XIX. extra page. pi. I, fig. 2 ; ? Hixcks, Ami. Mag. 



Xat. Hist., ser. 5, vol. VIII, p. 64 , pi. I, fig. 6 ; Waters, Quart. Journ. Geol. Soc, vol. XXXIX, p. 437 ; 



ibid.. vol. XLIII. p. 62 ; MacGillivray, Tert. Polyzoa of Victoria, p. 91. pi. XII, fig. 9. 

 Aimuhsa austràlis Julliex, Mission du Cap Horn. p. 59, pi. I, fig. 5, and pi. IX, figs. 3-4. 



(1) Zool. Chall. Exp., vol. X, pt. XXX. p. 127, pi. XXIV, fig. 2. 



