EEPORT ON THE MONAXONIDA. 153 



composed of smooth stylote spicules united together by a large proportion of horny 

 matter ; it is echinated by numerous smaller, spined styli, which project from the 

 surface at right angles (PL XLVI. fig. 9). 



Spicules. — (a) Megasclera ; of three kinds — (l) nearly or quite straight, rather slender, 

 sharply and gradually pointed styli, usually with slightly spined base ; measuring about 

 0"2 by 0"0065 mm., forming the dermal crust. (2) Smooth, slightly curved, stout styli, 

 measiiring about 0"3 by 0"018 mm., forming the main skeleton. (3) Small, straight, 

 entirely spined styli, measuring about 0"1 by O'Ol mm., echinating the skeleton fibre. 

 (h) Microsclera; of two kinds, (l) Minute, palmate isochelse, about 0'016 mm. long. 

 (2) Very long, slender, hair-hke toxa, usually occurring in very loose bundles, length about 

 0*16 mm. These are the most characteristic spicules of the species, and it is from their 

 hair-like nature that the specific name has been taken. They may at once be recognised 

 as toxa by the sharp bend in the centre. 



From the same station as this sponge comes a species of Pachychalina, which so 

 closely resembles the specimen of Rhaphidophlus Jilifer in external appearance as to be 

 very readily mistaken for it (compare PL IV. fig. 1 with PL XXVIII. fig. 2). This close 

 resemblance in external form between two such widely different species is very remarkable. 

 The Pachychalina is a shade lighter in colour than the Rhaphidophlus. 



This species resembles Mr. Carter's common Australian species Echinonema typicum,^ 

 the latter is, however, of a much more luxuriant growth, and the proportions of the 

 spicules also difier. According to the original description there are no chelae or toxa in 

 Echinonema typicum, and only two forms of megasclera, but an examination of the dried 

 types in the British Museum has given us good reason for asserting our belief in the 

 presence of both forms of microsclera. We have not, however, found sufficient grounds 

 for an identification. A redescription of Echinonema typicum from spirit specimens is 

 much needed. 



Loco%.— Station 208, January 17, 1875; lat. 11° 37' N., long. 123° 31' E.; 

 Philippine Islands ; depth, 1 8 fathoms ; bottom, blue mud. One specimen. 



Rhaphidophlus lohatus, Vosmaer, sp., var. horrida,^ nov. (PL XXVIII. fig. 1 ; 

 PL XXIX. figs. 4, 4a, 46, 4c). 



1880. Clathria lobata, Vosmaer, Notes from the Leyden Museum, vol. ii. p. 151. 

 Sponge (PL XXVIII. fig. l)stipitate, compressed, palmate, dichotomously branching. 

 The stem, which is about 6 mm. in diameter, springs from a flattened and slightly ex- 

 panded base and divides into two at a height of two inches from the ground, each 

 branch again subdividing. Total height of specimen 106 mm.; breadth at the top (the 

 broadest part) 44 mm. Colour in spirit light, greyish -yellow. Texture fine, fairly 



1 Ann. and Mag. Nat. Hist., ser. 5, vol. vii. p. 378. 



2 So called from the bristling appearance of the surface when seen under a low pofl'er of the microscope. 



(ZOOL. CHALL. EXP. PART. LIX. 1887.) Kuu 20 



