HYDROID ZOOPHYTES. 17 



Bonnevie (5 : pp. 469-471) in 1898 instituted the genera Lampra and Gymmgonos. 

 This authoress includes all the species belonging to this group of genera with 

 " medusoid " gonophores in the genus Corymorpha. All species with " pseudo- 

 medusoid " gonophores are placed in the genus Lampra, and those with " styloid " 

 gonophores in the genus Gymnogonos. 



This classification appears to us to be reasonable and will probably serve a useful 

 purpose for some years. Difficulties are sure to arise later when species are found with 

 intermediate characters, but at present we can recognise three distinct steps in the 

 degeneration of the medusiform gonophore which may be used for purposes of 

 classification. There is the " medusoid " gonophore showing some evidence of 

 degeneration, but retaining the endocodon or sub-umbrella cavity, the " pseudo- 

 medusoid " gonophore retaining the umbrella wall, but with no sub-umbrella cavity ; 

 and, lastly, the " styloid " gonophore with little or no definite trace of medusoid 

 structure. 



Lampra parvula. 

 (Plate III., figs. 15, 16 ; and Plate IV., fig. 35.) 



Localities. — Ofi" Hut Point and Flagon Point in McMurdo Bay. Sexually mature 

 and full-grown specimens obtained from September to December, 1902, and September, 

 1903. Young specimens obtained January, February, March and October, 1902, and 

 January, 1903. Depth, 10-20 fms. 



A great many specimens of this interesting little species were found in several 

 tubes and bottles from the localities named above. They are attached by root-like 

 processes from the basal end to polyzoa (fig. 15) and to a curious felt- work mass of 

 substance that is mainly composed of sponge spicules (fig. 16). Although Lampra 

 parvula presents us with the largest hydroid zooid, except those of L. microrhiza and 

 of Tuhularia in the collection, yet they are considerably smaller than the zooids of any 

 known species of Lavipra or Corymorpha. The zooids of the only known species of 

 Gymnogonos, however, are only 10-20 mm. in height. Like many other species of 

 Corymorphidae, the colour of the spirit specimens is dark reddish-brown. 



In habit the species closely resembles Lampra socia (Swenander, 23 : pp. 6-8, 

 figs. 1-2) from the Trondhjem fjord, several specimens being usually found in groups 

 more or less imbedded in the sponge debris mass. A few very young specimens were 

 found attached singly to the stems of calcareous polyzoa (fig. 15), or more rarely to 

 other hydroids. L. socia was found attached to the branches of L^ophohelia prolifera. 



Hydrosome. — The height of the full-grown polyps from the base to the mouth is 

 about 80 mm. 



In a great many specimens (fig. 16) there is a sudden diminution in the diameter 

 of the polyp about half the distance from the base to the tentacles. The position of 

 the constriction varies a good deal in different specimens, and in some it is hardly 

 noticeable, the stems gradually tapering from the base to the neck. The thicker basal 



VOL. III. -y E 



