194 CEYLON PEARL OYSTER REPORT. 



late skeleton with its strong development of spongin. It appears to form a connecting 

 link between the genera Acanthella and Phakcllia. 



I have little doubt of the specific identity of the Ceylon form with that from the 

 Red Sea, where it is, according to KELLER, one of the most abundant and charac- 

 teristic forms on the reefs. Such slight differences as T have observed will be 

 sufficiently evident by comparison of the description given above with that given 

 by KELLER (61), in 1889. KELLER tells us that the colour in life is blue. 



R.N. 31 (GulfofManaar). 



Auletta, SCHMIDT. 

 Axinellidse of tubular form ; without microscleres. 



Auletta lyrata (ESPER). 



1798-1806, Spongia lyrata, ESPER (6) ; 1870, Raspaigella lyrata, EHLERS (58) ; 1889, Auletta 

 aurantiaca, DENUY (3). 



There are a number of specimens of this species in the collection, which show it to 

 be an extremely variable one, both as regards external form and spiculation. The 

 re-discovery of the typical flabellate form, agreeing closely with ESPER'S figs. 1 and 2 

 (Plate 67), enables me to identify my Auletta aurantiaca with ESPER'S Spongia 

 lyrata, which was also obtained from Ceylon. 



Typical examples may be described as follows : 



Sponge erect, flabellate, shortly stalked. Lamella thick, slightly proliferous, with 

 broadly rounded margin bearing a row of small, sometimes sphinctrate vents, which 

 are the outlets of vertical oscular tubes. Surfaces of lamella rather minutely conulose 

 or rugose, and slightly hispid. Texture (in spirit) compressible and resilient, but 

 tough ; colour yellowish-grey. One specimen (R.N. 345) has a total height of about 

 31 millims., the lamella is about 42 millims. in breadth, and 7 millims. in thickness. 

 The vents are rather less than 1 millim. in diameter. 



The main skeleton consists of wispy bands of long, slender spicules united together 

 by abundant very pale-coloured spongin, running upwards and outwards to the 

 surface conuli (from which their terminal spicules project more or less) and connected 

 with one another by occasional short cross-fibres of one spicule's length, forming an 

 ill-defined, rectangular-meshed network of spicular fibre. In these fibres the spicules 

 lie approximately parallel to one another, there being none of the typical axinellid 

 arrangement except in the surface brushes. Between the fibres, which have a very 

 loose, irregular appearance, numerous isolated spicules are scattered. 



Spicules. (1.) Styli ; long and very slender, nearly straight; evenly rounded off 

 at the base and fairly sharply pointed at the apex ; size about 0'41 millim. by 0'005 

 millim., but variable. 



(2.) Slender oxea ; variously ended ; mostly a good deal shorter than the styli. 



,A second specimen (R.N. 174) differs in having the margin of the sponge thinner, 



