1910.] FROM MEIIGUI ARCIlirEI.AGO. 803 



are ax^raiigetl ia two series, the polyps of one series alternating 

 witli those of the otliev. The aperture faces outwards and 

 iipwards, is slightly elliptical in shape, and has an even margin, 

 indicating the boundary between the thicker perisarc and the 

 place where the chitinous coat becomes so thin and delicate that 

 it follows the movements of the polyp. The perisarc throughout 

 is covered by a thin coating of extraneous material — diatoms, 

 sand -grains, fragments of sjionge-spicules, and such like. 



The hydrauths are much contracted, and in this state exhibit 

 a pyriform body with well-developed hypostoiue. The tentacles 

 appear to number about forty. 



Gonosome unobserved. 



Colour, in alcohol, grey. 



Dimensions : — 



Diameter of branehlets immediately above origin 0-3 1-0-38 mm. 



„ hydranth tube 0-25-0-31 mm. 



Hydranth, length 0-52-0-98 mm. 



,, diameter 0-21-0-42 mm. 



IS ematocysts on tentacles, length 5 /x,. 



,, ,, breadth 3 /x. 



Locality. Three small colonies, with hydi'orhiza embedded in a 

 sj)onge, were found at St. 35, between Warden Island, Howe 

 Island, and Lyall Island, 15 to 20 fathoms, rock and sand. 



So little is known of the vai-iation liable to occur in the indi- 

 vidual species of this genus, that it is difficult to fix on definite 

 specific characters. In this case, I have I'elied mainly on the 

 structure of the tubes from which the hydranths project. In 

 the majority of the species of Corydendrium so far described 

 these are free for a considerable distance beloAs^ the hydranth : 

 but here the tubes are adnate up to the end. This gives to the 

 branches a dumpy appearance, unlike the lax grow'th of other 

 species. \\\ this respect it approaches most closely C. corrugaium 

 Kutbiug (1905, p. 941), which is to be distinguished, however, by 

 its distinct " hj'drophore-like structures," which are " usually 

 distinctly corrugated with deep irregular annulations " ; by the 

 presence of a well marked annulai- constriction near the origin of 

 the branches ; and by the large size (5 inches) of the colonies. 



The species, Solenwpsis dendriformis, described by me in 1907 

 (1907, p. 494) as representing a new genus, under the erroneous 

 supposition that Corydendrium gave rise to gonophores with free 

 medusfe — I had been unable to refer to the magnificent description 

 of Weismann (1883), — obviously belongs to the genus Cory- 

 dendrium, as Dr. Stechow has recently pointed out (1909, p. 9). 



Corydendrium dendrifo)'mis differs from C. 2^<^<'^'<-(siticuni in 

 possessing- thick, definite stems, with branehlets arranged in 

 pseudo-pinnate fashion, and in having the free portion of the 

 tubes from which the hydranths project much shorter than those 

 of C. parasiticum. 



