14 SYDNEY J. HICKSON. 



There can be no doubt that this specimen belongs to the same species as those 

 described by Kolliker (7) under the name Umbdlul<i <;ir/>,'iifn'i. These specimens were 

 live in number, and found by the 'Challenger' at depths of 1975 fathoms and 1950 

 fathoms in the south polar seas; the stage of growth of the 'Discovery' specimen 

 being probably an older one than specimen E of the ' Challenger ' series. 



But although we may be satisfied to give the specimen Kolliker 's name, the careful 

 description by Dr. Jungerseu (6) of a series of specimens of the north polar and deep 

 Atlantic species, U. encrinns, has impressed me with the belief that in time these two 

 species (U. encrinus and U. carpcntcri) will be merged into one. There is no doubt that 

 they are closely related, but as accident has prevented me from further testing this 

 opinion I must leave the problem for others to consider. The striking similarities in 

 structure between these north and south polar forms of Umbellula is, however, a matter 

 of theoretical interest. 



LIST OF MEMOIRS QUOTED IN THE TEXT. 



1. Gray, J. E. Catalogue of the Lithophytes in the British Museum, (1870). 



2. Hickson, S. J. Trans. Zool. Soc. LoncL, XIII., (1894), p. 338. 



3. Hickson, S. J. ' Southern Cross' Collections, 11)02, p. 293. 



4. Hickson, S. J. Marine Investigations in S. Africa, the Alcyonaria, Pt. II., (1904), p. 224. 



5. Hiles, I. Willey's Zoological Results, Pt. II., (1899), p. 19C. 



C. Jungersen, H. F. E. Pennatulida, Danish Ingolf Expedition, Vol. V., (1904). 



7. Kolliker, A. Penuatulida, ' Challenger' Eeports, Vol. I., (1880). 

 7A. Kolliker, A. It-ones Histologies, 18G4-5. 



8. May, W. Hamburger Magalhaensische Sammelreise, Alcyonarien, (1899), p. C. 



9. Roule, L. ' Southern Cross' Collections, 1902, p. 290. 



10. Studer, T. Monatsber. K. Akad. Wiss. Berlin, 1878, p. fif.2. 



11. Thomson, J. A., and Ritchie, J. Trans. Roy. Soc. Edin., XLI., (190G), p. 851. 



12. Valenciennes. Voyage sur la Venus, 1846 (fig. only). 



13. Versluys, J. Siboga Expeditie, Mon. XIIlA., (100(3). 



14. Wright, E. P., and Studer, Th. Alcyonaria, ' Challenger ' Reports, Vol. XXXI., (1889). 



DESCRIPTION OF THE PLATES. 



PLATE I. 



FKJ. 1. UmMlula carpcntcri (reduced to \ size). An, Crown of Autozooids ; It., Peduncular bulb. 

 2. U. carpenter/,. Proximal view of crown of autozooids. Natural size. Si., Petaloicl area of 



siphonozooids ; D., Dorsal pctaloid area terminating in a large siphonozooid ; F., Ventral 



petaloid area ; G., An autozooid that was injured, the tentacles missing. 



3. U. carpenter/. Distal view of the crown of autozooids. a, the ninth or " Haupt " zooid. 

 4. U. carpenter!. Four siphonozooids of the petaloid areas, lent., the single long tentacle of each 



siphonozooid, X 40 diams. 

 5. U. carpenter!.. Transverse section of one of the siphonozooids of a petaloid area, x 120. Si., 



Siphonoglyph ; d. ?., Dorsal mesenteries. 



,, (!. U. carpenter!. Transverse section of a small siphonozooid of the peduncular bulb, X 120. 

 7. U. carpenter!,. One of the tentacles of an autozooid, to show the arrangement of the pinna', X 2$. 

 8. Primnoella dicergens. Two whorls as seen in a spirit specimen, showing the manner m which 



the scales project on the surface, X 10. 



,, 9. Priinniii'llii ilirrrgms. A spicule of the calyx, X - r >0. 

 lo. -Primnoella divergens. A spicule of the cocnenchym, x >o. 



