472 MOLLUSCA OF MAST HEAD REEF, QUEENSLAND, I., 



Flab. — A few separate valves from 17-20 fathoms. 



Obs. — The occurrence of a Philobrya in the coral fauna was 

 unexpected. P. recapitula belongs to a group of radiate, inflated 

 asymmetrical species of which the New Zealand P. costata was 

 the first known. The exquisite sculpture will readily distinguish 

 the present species, whose individuality is further marked in the 

 hinge and complicated prodissoconch. The median spike of the 

 latter presents inferences of wide interest. The hollows on the 

 summits of the prodissoconch caps of certain species, for example, 

 Condylocardia concentrica Bernard,* and Philobrya parallelo- 

 grammaj may, it is now suggested, be the scars from which 

 similar spikes have been shed. Such a spike appears on the 

 prodissoconch of Cyclopecten obliquus.\ 



Three stages of embyronic life are recorded in the prodisso- 

 conch of P. recapitula. The spike may be the stage for which 

 Kesteven has proposed§ the name of veloconch. 



MODIOLARIA PERSTRIATA, n.Sp. 



(Plate xxxvi., figs.9-10.) 



Shell small, thin, oblong-elongate, rather inflated, umbo much 

 incurved, situated at the anterior extremity. Colour, cream, with 

 a few scattered brown spots. The unsculptured area characteristic 

 of the genus falls within the anterior third; it is here reduced to 

 a narrow ray the width of three grooves and ridges. Sculpture: 

 the specimen drawn has, posterior to the smooth ray, 104 sharp 

 raised radial threads parted by deep grooves of equal breadth. 

 The threads increased in size with the growth of the shell and 

 are largest at the posterior dorsal angle. New threads appear 

 by intercalation. The margin is finely crenulated by the radial 

 sculpture. Anterior to the smooth ray are 18 similar threads 

 and grooves. The radials are crossed and broken by about 40 



* Journ. de Conch., xliv. pi. vi. 



t These Proceedings, Vol. xxx., pi. xxxii., fig. 16. 



% Mem. Austr. Mus. iv., p.306, fig. 51. 



§ These Proceedings, xxx., p. 327. 



