STUDIES ON THE COMPABATIVE ANATOMY OF SPONGES. 177 



apart from the fusion of the individuals, closely resembles 

 that ofUte argentea, as figured by Polejaeff(8). A horizontal 

 section of the colony shows a number of circular spaces 

 scattered at intervals, generally, but not always, in a single 

 row. These are the gastral cavities of the Syconoid individuals 

 cut across. Each cavity is surrounded by its own radial 

 chambers, arranged in a perfectly normal manner, except for 

 the fact that on the adjacent sides of any two neighbouring 

 gastral cavities the chambers are much shortened, and some- 

 times appear bent outwards as though to avoid one another. 

 The inhalant pores are scattered over the dermal surface, and 

 lead into irregular canals, which pierce the thick cortex to 

 reach the radial chambers. At their lower ends the gastral 

 cavities of the fused Syconoid individuals all communicate 

 with one another, indicating that this peculiar form of colony 

 has arisen from fusion of adjoining individuals of a branching 

 colony. The radial chambers are approximately octagonal in 

 transverse section, while the much smaller '' intercanals " 

 between them are square. The exhalant openings of the 

 chambers are protected by very well-developed diaphragms, 

 and each gastral cavity has also a single large, well-developed 

 diaphragm situate just within the osculura. 



Probably Synute pulchella is the only known example of 

 a calcisponge with a Syconoid canal system, which has become 

 at all strikingly modified in accordance with the principle set 

 forth in section 8 of the scheme given above. 



Utella. 

 This genus, founded entirely on skeletal characters for the 

 reception of HaeckePs Sycandra hystrix, and perhaps also 

 Schmidt's Ute utriculus (5), presents no features of special 

 interest in its canal system, which appears to conform to the 

 ordinary corticate Syconoid type, like that of Grantia. 



Anamixilla. 

 This genus is also founded entirely on skeletal characters, 

 and the only known species, A. torresi, Polejaeff (8), appears 



