128 Memoirs of the Indian Museum. [Vol. V, 



Only two genera can at present be assigned to this family, namely Urnatella, 

 Leidy, from fresh water in North America and Loxosomatoides , Annandale, from 

 brackish water in India. 



Genus LOXOSOMATOIDES, Annandale. 

 1908. Loxosomatoides , Annandale, Rec. Ind. Mus. II, p. 14. 



Since this genus was described I have been able to compare specimens of Urna- 

 tella with the types. The relationship between the two genera is evidently very close 

 and is shown even in the minute structure of the lophophore and tentacles and in 

 the position of the different parts of the alimentary canal. I have not been able to 

 detect any trace of a brood-pouch in Loxosomatoides and there is a distinct cloaca, most 

 readily seen when the rectum is in a retracted condition. Spaces occur in the lopho- 

 phore that are clearly homologous with the water-vascular system of Urnatella ' , and 

 tentacular retractors are conspicuously present. 



Urnatella, therefore, differs from Loxosomatoides mainly in the segmented stalk 

 of its polyps and in not possessing either an elongate stolon or a chitinous capitular 

 shield. 



Nothing is known of the embryology of either genus, but the asexual method 

 of reproduction is similar, though not identical, in the two. In Urnatella the stalks 

 of the polyps segment to form resting buds, while in Loxosomatoides buds are formed 

 by the degeneration of capitula. It is not yet certain whether any capitulum may 

 degenerate for this purpose, or only certain capitula do so, and I have no information 

 as to the stage in the development of the capitulum at which degeneration com- 

 mences ; but it is noteworthy that in one instance a stalk was observed which bore 

 three resting buds, arranged in a linear series one in front of the other at its ex- 

 tremity. It is perhaps legitimate in any case to regard the capitulum in Urnatella as 

 the homologue of a single segment of the stalk, or rather to conceive of the segment 

 as a degenerate capitulum. 



The species of Loxosomatoides that occurs in the Chilka Lake and the lagoons of 

 Madras is not identical with the one described from the Gangetic delta, but the 

 two are closely related. They may easily be distinguished one from the other 

 by the complete absence from the capitular shield of the Peninsular species 

 (L. laevis) of the spines that always occur on that of L. colonialis, and by the much 

 more regular ornamentation of the shield in the former species. The normal method 

 of growth is also different, for whereas the polyps in L. laevis are borne singly at 

 considerable intervals on stalks that arise from one side of a slender rhizome which 

 branches sparingly, in L. colonialis, though the unilateral arrangement also obtains, 

 the polyps are arranged in groups and the rhizome from which their stalks arise 

 is somewhat flattened and irregular and branches rather less sparingly. These 

 characters are liable to be obscured if growth is congested or inhibited, but they 

 never disappear altogether. 



Davenport, Bull, fyfus. Comp. Zool. Harvard XXIV, pp. 1-44, pis. i-vi (1893). 



