14 THE VOYAGE OF H.M.S. CHALLENGER. 



I cannot accept Dr. Jullieu's name origella, as I consider that he uses it for two things 

 physiologically quite distinct, for to the rosette plates pass thin protoplasmic threads, 

 whereas the tube pores contain a fluid with corpuscles. 



With regard to the importance of " origelles evolutives" represented by the rosette 

 plates, I am at one with Dr. Jullien, and have mentioned and figured many, both recent 

 "and fossil in my various papers, and do not consider a species is completely described 

 until they are given. It of course often happens, especially with paleeontological work, 

 that there is not material available or in a state of preservation to admit of complete 

 description. I have, however, made preparations of many hundred species, and find that 

 besides the number of plates on both the lateral and distal walls, the position and shape 

 is of value. They may be surrounded by a ridge or band, and in the plate there may be 

 one or many points of communication. In some cases they occur in a rather long tube 

 leading from one zocecium to another, as, for instance, in the distal rosette plates of Porella 

 cervicornis, Ellis and Solander, but I have not before come upon any with such a large 

 projecting cover as in Vincnlaria labiata. The character of these plates should be used 

 with others, and not overrun, and by making us more sure of our species may indirectly 

 help us with genera, and in some cases may be generically important, but not in all. 



The lip rises up to the level of the operculum which rests upon it, thus forming a 

 Microporidan aperture, and I should prefer to call it Micropora, but as I suppose Mr. 

 Hincks would place it under Thalamoporella, I provisionally follow him. 



Besides the lip, which projects upwards, the front wall of the zooecium is directed 

 downwards (PI. II. fig. 33), thus contracting the zooecium near the aperture ; in Stegano- 

 porella neozelanica the front wall turns some distance down into the zooecial chamber, 

 which has been described as divided into two chambers, but in this last species the 

 calcareous wall again turns up to the base of the oral aperture enclosing an empty space 

 between the fold (PL II. fig. 32). In Micropora impressa, Moll., the spaces forming 

 the so-called pores project into the zocecial chamber, causing a contraction at each side, 

 but no median contraction as in the other two (PL II. fig. 34). 



Bifaxaria submucronata. Busk (PL I. fig. 6 ; PL III. fig. 18). 



Bt/axaria submucronata, Busk, Zool. Chall. Exp., part xxx. p. 80, pi. xiii. fig. L 



A specimen sent to me from Station 122, 350 fathoms, has immersed ovicells, 

 occurring as simple enlargements of the zooecia. In pieces calcined the zooecia some- 

 what separate, and then it is seen that the avicularium is at the base of the zoarium with 

 a corresponding notch in the peristome, of the zooecium below. Mr. Busk describes the 

 zooecia as subcarinate, but this is from a deceptive appearance caused by the contraction 

 of the outer membrane in drying. 



I use the name Bifaxaria merely to indicate the species examined, but do not think 



