22 DE. T. S. COBBOLD ON CCENUETJS. 



Several specimens of this small species of Serpula are in the 

 collection of the Museum, the slender tubes creeping on frag- 

 ments of old oyster-shells. The operculum is the only part of the 

 animal preserved, as the specimens were transmitted in a dry 

 state. Like that of the other known species of true Serpula, it is 

 finely crenated on the margin. The crense are twenty in number, 

 but the grooves externally are confined to the surface of the disk 

 itself, and are not extended to the pedicel or stalk. The tube is 

 slender, nearly round, with only a slight keel running longitu- 

 dinally along its dorsal surface. It is white, the mouth is nearly 

 circular, and the ' shell itself is strongly marked along its whole 

 length with transverse flexuous striae which encircle it. 



The specimens in the collection are grouped together on the 

 old oyster-shell, and mixed up with numerous specimens of zoo- 

 phytes, Alcyonia &c. Most of them are more or less incrusted 

 with these substances. Length of the tube about 16 lines ; cir- 

 cumference about 1 line. 



Hob. New Zealand. (Brit. Mus.) 



EXPLANATION OF PLATE II. 

 Fig. 1. Cymospira tricornis, operculum. 



2. C. brachycera, operculum. 



3. C. MacGillivrayi, mouth of tube, in coral. 

 4, 5. Pomatostegus Bowerhanki, operculum. 



6. Serpula Juhesii, operculum. 

 7, 8. S. Narconensis, operculum. 

 9. 8. Zelandica, opercvUum. 



10. JEupomatus Boltoni, operculum. 



11. Qaleolaria decumbens, operculmn. 



Note on Ccenurus. By T. Spenceh Cobbold, M.D., F.E.S., F.L.S., 

 Lecturer on Comparative Anatomy at the Middlesex Hospital. 

 [Read May 5, 1864.] 

 I BEG to call the attention of the Society to a specimen of 

 Ccenurus obtained from the viscera of an American Squirrel which 

 died at the Zoological Grardens, Regent's Park, several years 

 back. In doing so, my object is partly to correct the opinion, stUl 

 very generally held, that there is only one kind of Ccenurus, and 

 partly, also, to point out the time when the existence of a second 

 kind of Ccenurus was first demonstrated, and by whom, likewise, 

 the discovery was made. "When, in January 1859, I described to 

 the Society a large Ccenurus obtained from the viscera of a Mada- 

 gascar Lemur, I carefully abstained from theorizing on the subject, 



