HYDROIDS. 841 



Family Sertularidae. Genus Synthecium. 



10. Synthecium txihiger n. sp. (PL LXIX. fig. 4.) 



Definition : A Sijnthecium whose hydroCcaulus reaches a height of more than 4 cm. and 

 is pinnate, with rather distant, opposite pinnae, and nodes often obsolete or lost. The 

 distance between the hydrothecae varies; they are usually opposite, but sometimes alternate 

 in parts of the pinnae, tubular, with a rather long free portion, which is bent sharply 

 outwards, and have circular openings, directed outwards, with entire, everted rims often more 

 than one in number. The gonothecae are egg-shaped, but pointed at the free end, and 

 quite simple in outline. 



The species is kindred to 8. orthogonia (Busk) but differs from it in the shape of the 

 gonothecae and in the loss of the nodes. (12, p. 390; 8, p. 767.) 



Taken in many dredgings throughout the Archipelago in 20 — 40 fathoms. 



11. Synthecium maldivense n. sp. (PI. LXIX. fig. 5.) 



Definition: A Synthecium whose hydrocaulus reaches 20 cm. in height and is pinnate, 

 the pinnae being alternate and having each a hydrotheca in its axil ; whose hydrothecae are 

 borne on the stem as well as on the pinnae, often grouped in sets of two or three pairs 

 as an internode but at other times at even distances, opposite or alternate, long in shape, 

 adnate for the greater part of their length to the stem but not to one another, with the 

 outstanding part curved at right angles to the adnate part and varying in length though 

 always short, and have a vertical opening overhung by a membranous hood and often stronger 

 at the sides so as to give the impression of a pair of side teeth ; and whose gonothecae 

 are irregular elongate sacs of circular section with a tubular mouth which is sometimes funnel- 

 shaped, and arise both from normal hydrothecae and also from the stem between the 

 hydrothecae. 



This species is extremely variable both in compactness of growth and in the arrange- 

 ment and shape of its hydrothecae ; so much so, indeed, that, were there not a number of 

 specimens in the collection, I should probably have been led to describe it under two or 

 more names. As it is, the series between the extreme forms is complete. I am inclined to 

 think that it is greatly subject to the " vegetative variation " of Mr Gardiner. It is kindred 

 to S. tuba (Bale 7, p. 87), but is not in any of its forms exactly like any species already 

 known. It is common in the Archipelago, having been dredged in most of the Atolls in 20 

 to 36 fathoms, and taken on the reef at Hulule, Male Atoll, and Goidu, Goifurfehendu Atoll. 



Genus Thviaria. 



12. Thuiaria gracilis (Allm.) subsp. (6, li. p. 70). The angle in the hydrothecae is not 

 so sharp as that of the type, and the ridge within is less marked. 



Dredged at Hulule, Male Atoll, in 30 fathoms. 



13. Thuiaria tenuis (Bale) subsp. (7, p. 82). 

 The nodes are wanting in the specimens. 



Taken on a calcareous weed at Maradu, Addu Atoll, and on a Sertularia in a dredging 

 from 20 fathoms in N. Male Atoll. 



108—2 



