DENDY NON-CALCAREOUS SPONGES 111 



and sometimes, at any rate, ending blindly. Vents relatively large, about 2 mm. 

 in diameter, situated on the sides of the branches or the upper margin of the 

 plate, each the terminal opening of a deep, cylindrical oscular tube. Surface smooth, 

 covered by a closely adherent, translucent dermal membrane, through which the 

 subdermal reticulation shows faintly. Colour in spirit pale yellow, texture fairly firm 

 but friable. 



There are several pieces of this sponge in the collection, which, as they all 

 come from the same jar, probably belong to the same specimen. The largest, 

 represented in Fig. 12, is, as a whole, lamellar, measuring about 31 mm. in length, 

 20 mm. in height and 5 mm. in thickness (this being also about the usual 

 diameter of freely projecting branches). 



The main skeleton is a close, irregular network of single spicules, penetrated 

 by long ; multispicular fibres about 0-04 mm. thick. These fibres are numerous 

 and run for the most part lengthwise in the branches ; they also form a well 

 developed subdermal reticulation, with very irregular, unequal meshes. 



The dermal skeleton consists of single spicules, thickly and evenly scattered 

 through the dermal membrane, crossing one another at all angles, but not united 

 in a regular network. 



There is little, if any, spongin present. 



Spicules. Short and fairly stout oxea, slightly curved and gradually and 

 sharply pointed at each end, measuring about 0-1 by 0-006 mm., but often rather 

 more slender. 



This sponge reminds one rather of the European Reniera simulans, but differs 

 in the smaller size of the spicules and in the strongly developed reticulation of 

 spicular fibre. In this respect, like Reniera semifibrosa, it approaches the genus 

 Pachychalina. 



It also resembles, both in external form and spiculation, the new species 

 Siphonochalina minor, described below (cf. Fig. 15). The growth of the sponge, 

 however, is on a much smaller scale, and the arrangement of the main skeleton 

 is different, for in S. minor it is entirely composed of multispicular fibres. 



Register Number, Locality, &c. II. 8 (exact locality uncertain). 



20. Reniera semifibrosa n. sp. (Plate II., Fig. 13). 



The sponge forms massive, convex crusts, closely adherent to other objects or 

 hollow underneath. The finest specimen (R.N. XXXIII. 1, Fig. 13) has the form of 

 a deep, inverted cup, the margin of which has been broken away all round from the 

 substratum, while the interior is quite hollow and empty. The total height of the 

 specimen is 85 mm. ; the maximum breadth of the base about the same ; the thickness 

 of the wall of the cup about 15 mm. The wall of the cup is perforated by two large, 

 irregular apertures (natural) with rounded margins, which lead right through into the 



H 2 



