528 Hydroida Thecata from the Anaaman Islands. 



Gonosomp, — A few structures, apparently phylactocarps, 

 replace hydroclades towards the base of the stem. They are 

 ivided into regular internodes each with three nematopliores, 

 two lateral and one median and proximal. Unfortunately 

 no gonangia are present. These structures are readily seen 

 to be morphologically equivalent to hydroclades. 



Loc. 'Investigator,' Station 'lU, "lat. 10° 12' N., long. 

 92° 20' 30'' E., between the Andaman and Nicobar Islands. 

 Depth 606 fathoms. 



Halicornaria hians, Busk, var. profunda^ nov. 



Trophosome. — Considerable variations are exhibited by the 

 trophosome, but these seem in the main to be due to differ- 

 ences in age. The thecate internodes, while they are twice 

 as broad as long at the base of a hydroclade, gradually 

 lengtlien till at the distal end their length may be to their 

 brcadtli as four to one. The mesial sarcoiheca in mature 

 colonies is adnate almost to the lip of the hydrotheca, pro- 

 jecting bej-ond the margin as a short free spout; in young 

 colonies it does not reach even to the intrathecal ridge, and 

 at this stage closely resembles that of young colonies of 

 H. variabilis, Nutting''^. In all stages, however, its anterior 

 profile is concave, a character which distinguishes this species 

 from JI. lalti (Maiktanner-Turneretscher). 



The trophosome of this variety is distinguished from that 

 described and figured by Bale f by the greater length of the 

 thecate internodes compared with their diameter, the greater 

 depth and more erect posture of the hydrothecse, and the 

 greater distance which separates the intrathecal septum from 

 the base of the hydrotheca. The less prominent nature of 

 the marginal teeth and the small size of the colonies (4 cm.) 

 are variations of little significance. 



(jonosome. — The gonangia, which have not hitherto been 

 desciibed, are quite unprotected and are borne on very short 

 stalks, one at the base of each hydroclade. In shape they 

 are saucer-like, convex beneath, concave above, appearing as 

 perfect disks, up to 0*38 mm. in diameter, when viewed from 

 the anterior of the colony. 



Loc. Andamans, 1899. 



* Nutting, C. C, " American Hydroids.^Part I. The PhimularidfE," 

 Smithsonian Institution, Special Bulletin (Washington, 1900), p. 127, 

 pi. xxxiii. iig. 7. 



t Bale, W. M., 'Catalogue of the Australian Hjdroid Zoophytes' 

 (Sydney, 1884), p, 179, pi. xiii. fig. 6, pi. xvi. fig. 7. 



