456 



THE STATOBLAST AND ITS DEVELOPMENT. 



In all respects, this is a remarkable species. Instead of hiding in darkness and 

 coveting the shade, as is the case with nearly all the polyzoa, the Cristatella exults in 

 light, and loves to crawl in shallow waters where it is exposed to the full blaze of the 

 meridian sun. The ordinary length of the Cristatella is from one to two inches, and its 

 general aspect reminds the observer of a yellowish brown hairy caterpillar, softer than 

 the well-known woolly bear, or larva of the tiger-moth, and indeed looking much as if it 

 were made from the soft silken substance denominated " chenille." 



It is one of the fresh-water species, and, as may be seen by reference to the illustra- 

 tion, the plume of tentacles is not funnel-shaped, but formed as if set in a horseshoe. 



Immediately below the Cristatella at fig.B, may be seen a rather formidable object 

 surrounded with grapnels, and termed a " statoblast." This again is a most marvellous 

 production, and requires some explanation. The statoblasts are developed within the 



POLYZOA, IX. 



A. Cristatella muc6do. X B. Cristatella rnucSdo. (Statoblast. X) C. L6phopus crystallinus. X 



D. & E. L6phopus crystallinus. (Statoblast. X) F- L6phopus crystallinus. (Ou rootlets of Duckweed. 



The sign X signifies that the object is magnified. 



cavity of the parent, where they may be seen of different sizes, and in most cases arranged 

 like beads on a string. They consist of two nearly hemispherical or oval discs, which 

 are united at their edges, and the line of junction strengthened by a more or less deep 

 ring, so that the general aspect of the statoblast is not unlike that of the planet Saturn, 

 as may be seen by reference to figs. D and E, and which give two views of the stato- 

 blast of the animal beneath which they are placed. 



In the Cristatella and another genus, the Pectinatella, the statoblast is armed with a 

 double series of hooks, starting from the edges of the discs, those of the opposite discs 

 alternating with each other and extending well beyond the ring. The spines are gradu- 

 ally developed, and force their way through an enveloping substance which surrounds 

 the statoblast. After a while it often happens that the soft, gelatinous envelope is 

 washed away and the statoblast assumes the appearance exhibited in the illustration. 



These wonderful objects contain the future young ; and the process of development 

 is briefly as follows : Within the walls of the parent they attain their full size, and 



