SPONGES. 91 



(3.) Anatriienes (Plate III., fig. 4, c, <') : of" ordinary form, with short cladi and 

 very long, slender, hair-like shaft. A specimen in a boiled-out preparation has cladi 

 about 0"037 millim. long and shaft about 2"8 millims. long. 



(4.) Oxea of the main skeleton (Plate III., fig. 4, e) ; stout, straight, fusiform, and 

 tapering very gradually to the extremities, which may be sharply pointed, or rounded 

 off or irregular; size about 3'1 millims. by - 046 millim. 



(5.) Sigmata (Plate III., fig. 4, h) ; slender, more or less contort, measuring about 

 0"017 millim. from bend to bend; abundant. 



(G.) Small scattered oxea (microxea) (Plate III., fig. A,f,g); straight or slightly 

 curved ; smooth, slender, fusiform, gradually and finely pointed at each end ; size 

 about 0'23 millim. by 0'005 millim. These spicules are scattered irregularly in 

 enormous numbers throughout both choanosome and ectosome ; in the latter position 

 they may form quite a dense layer at the surface of the sponge, in which most of 

 them lie tangentially. They may, perhaps, be regarded as microscleres. 



Stained sections show that there is no cortex, and that the ectosome, though 

 fairly thick, is not sharply differentiated from the choanosome. The material is not 

 in a fit condition for minute histological investigation, but I have been able to make 

 out that the flagellate chambers are oval and about - 029 millim. in greater diameter. 

 The inhalant pores are apparently scattered over the surface, and the inhalant canals 

 appear to originate in irregular lacunar subdermal cavities. The larger exhalant 

 canals are provided with numerous diaphragms, and terminate below the sieve-like 

 floor of the cloaca. 



The most characteristic features of this species are the structure of the cloaca and 

 the presence of the very numerous smooth microxea. In Tetilla (?) australiensis 

 (Carter) minutely spined microxea, - 21 millim. long, are present, and Sollas (15, 

 p. 43) observes of this species that the oxeote microscleres are almost unique amongst 

 the Tetillkke.* The case of T. hirsuta, described above, however, seems to show that 

 in the oxea of this genus (as in PlakinastreUa, &c.) it is impossible to draw a hard and 

 fast line between mega- and microscleres. 



In addition to the type described above, there are in the collection two other 

 specimens which may be referred to the same species, viz., Pt.N. 189 and 205. Both 

 are somewhat imperfect. R.N. 205 has several cup-shaped (cloacal ?) cavities, with 

 sievedike floors, irregularly distributed ; the other is too imperfect to show the 

 character of the vents. 



K.N. 189 (Muttuvaratu Paar, Gulf of Manaar) ; 205 (Gulf of Manaar) ; 230 (deep 

 water off Galle and onwards up West Coast of Ceylon). 



Tetilla anomala, n. sp. Plate III., fig. 5. 



There are two specimens of this sponge in the collection, the larger of which 

 (R.N. 153) may be regarded as the type. It appears to be a fragment, amounting to 



* (Jxeotu microscleres occur also in the genus Pwatetttla (vidt infrd). 



