and Acajndco Sponges, 277 



throughout, while the spicuhition above stated is always the 

 same. 



It is often accompanied in its repent-incrusting form by 

 Thalysias carbonaria^ de F. et }*L.,=^ Spongia carbonaria, of 

 Lamarck, who states that it is found " enveloppant de grandes 

 portions du Millepora alcicornis^^ (v^ol. ii. p. o57. no, 20) ; 

 but the friable structure of the latter, as well as its colour, 

 although in every other respect like Chalina rubenSj distin- 

 guishes the two ; while the lighter-coloured species of Thali/- 

 sias are still more compact and friable, although still with tlie 

 same spiculation and structure. Yet Thalysias has been 

 placed by me in tlie order Holorhaphidota, and Chalina in 

 that of the E.ha]jhidonemata ! simply because the absence of 

 friability in the latter arises from the kerasine element in the 

 fibre preponderating over the spiculiferous core, while in the 

 Holorhaphidota it is' the opposite. 



This is the case with the British species Halichondria 

 simuIanSj Johnst., whose varieties are so numerous that he 

 calls it ''polymorphous." Indeed //. simulans is not unlike 

 a British representative of the West-Indian Chalina rubens. 

 So it is with a sponge similar to H. simulans at Ceylon 

 (? Hartog Is., W. Australia) and Port Elizabeth respectively, 

 but with a bihamate flesh-spicule, in which the former has 

 the resiliency of a Chalina and the latter that of an Isodictya 

 (numbered respectively in the British ]\Iuseum 106, registered 

 59. 2. 28.36, and 202, registered 71. 5. 12. 1). 



Chalina ruhcns also exists in the sea about S. Australia ; but 

 the specimen which I have is of a light yellow colour; however, 

 it seems, like the West-Indian specimens, to come nearer to 

 the British species Halichondria lyahnataj Johnst., which I 

 have taken for the type of the group Palmata (viz. no. 2) in 

 my order Ehaphidonemata. 



Family 2. Cavochalinida. 

 Tuba lineata, de F. et M. (p. 74), 



Vase-shaped, flabelliform, compressed orbivalvate, wdth the 

 halves, which are thin and separate, in close approximation, 

 but marginally united on one side only and at the base of the 

 Pecte/i-like form. Size about 9 inches long by 6 inches high. 

 (Spicule, PI. XI. fig. 4.) 



Loc. Dominica. 



Tuba diyiialis, de F. et M. (p. 49, ])1. viii. fig. 2). 



Vase-like or tubular, patulous, proliferous, consisting of 

 several individuals of different sizes grou})ed together, so as to 

 Ann. & May. N. Hist. Scr. 5. ]'ul. ix. 20 



