30 PODOCORYNID^:. 



WE have had conflicting accounts of this zoophyte from 

 authors, their discrepancies being due to the fact of their 

 having observed it in different stages of growth. Sars 

 describes the polypites as united together by a kind of 

 incrusting mantle, which after their death remains behind 

 ' ' as a brown epidermal investment, bearing numerous 

 pointed spines of a horny nature/' Allman regards this 

 as probably a mistake, and characterizes the hydrorhiza 

 as simply tubular and retiform. But Podocoryne presents 

 us with both conditions. In its younger state the poly- 

 pites rise from delicate milk-white fibres, which run in 

 nearly parallel lines over the surface of the shell that bears 

 the zoophyte, and which are united by cross fibres, forming 

 at first a rather wide-meshed net. These cross fibres in- 

 crease in number and often anastomose, and gradually the 

 meshes are filled in by a chitinous crust, which appears to 

 involve the tubular basis itself. Numerous pointed spines 

 are developed simultaneously, as it seems, with the growth 

 of the crust ; at least I have never noticed them when the 

 stolonic network was perfectly simple. They are not muri- 

 cated, like those of Hydractinia, but smooth. In this way 

 the common base becomes a continuous expansion, thickly 

 studded with spinous processes, as described by Sars, on 

 which the polypites are densely crowded together. I have 

 specimens overspreading the shells of Nassa reticulata, 

 that exhibit the two conditions side by side. The delicate 

 milk-white network of fibres covers a considerable portion 

 of the surface ; but at certain points the meshes may be 

 seen partially filled in by the crust, while at others they 

 are converted into a solid expansion. 



The stolonic portion, then, of Podocoryne cornea occurs 

 under the following forms : (1) as a network of fibres of 

 greater or less complexity ; (2) as a network the fibres of 

 which are involved in a chitinous crust, which partially 



