TBTRAXONIDA. 51 



SUB-FAMILY RENIERINAE, RIDLEY AND DKNDY. 



PYLODERUA. 

 (paw) Ridley and Dendy (15. p. 6). 



Renierinae with a paivhment-likc, easily-separated, dermal mcinltniiic in which 

 are situate*! closely-packed tangential oxeas, and with distinct round or oval pore areas. 



I'M "I-KRMA LATRUNCULJOIDBB. 

 1887. HMrkontlrM hitrunruliouit*, Ridley and Dendy (15. p. 6, PI. I., li-. :.. A.M. 



There in one Haltcllate specimen attached to a small stone. The height is (> cm., 

 the width at the upper rim 5*5 cm., and the thickness 1 '8 cm. The osculet*, generally 

 contracted into little white conules, are scattered about among the pore areas, and not 

 !.'! i "ii t :.< !_' .1 ,n tli-- i h.ili.'irj- 1- exunplec, Each oKoIar opening lead 

 into a smooth funnel-like cavity with a sharp-edged circular sphincter-like opening at 

 the boa. 



The strongly marked characters of this peculiar species seem to me to necessitate 

 its removal from I/alichotulria and its inclusion under a new genus. In the ' Challenger ' 

 Report Ridley and Deudy state that they were at first doulitful whether the arrange- 

 ment of the pores in definite areas would prove to be a character of generic importance, 

 and finally decided that this feature was only one of adaptation. Prof. Dendy has 

 since told me that he now thinks that this species should be placed in a distinct genus, 

 and in this opinion I concur. There are no microscleres to help in tracing its affinities 

 and the body skeleton is Reuierinc in character ; accordingly it is for the present placed 

 among the Renierinae. 



Dredged off Coulman Island in 100 fms. The ' Challenger ' obtained specimens 

 from a depth of GOO fms. off the mouth of the Rio dc la Plata. 



PETROSIA FISTULATA. 



(Plate XVIII., figs. 4, 4a-b,and Plate XXIV., fig. 7.) 

 1907. Petrotia fitlulaia Kirkpatrick (lOa. p. 290). 



Sponge tubular. Surface smooth, showing the round openings of the inhalant 

 canals about 4 mm. in diameter and close together. 



Inner surface of the tube of the sponge finely or rarely coarsely pilose, and 

 showing the round openings of the exhalant canals about 1 mm. in diameter. Colour 

 in spirit, pale yellow. Texture firm, but slightly compressible. Eurypylous 

 flagellated chaml>er8 spheroidal, 24 5 n in diameter. 



Skeleton formed of main fibres proceeding from the inner to the outer surface, 

 joined by secondary fibres one spicule thick, so as to form obscurely quadrangular or 

 hexagonal tubes about 5 mm. in diameter ; ends of spicules cemented with spongin. 



Spicules. Oxeas, 492 x 24*4 /*, bent usually, or curved at centre, sub-tornote. 



