ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 235 



Coelenterata. 



Cladonemidge.* — Dr. C. Hartlaub believes tbat tbe Cladonemidse are 

 one of tbe most interesting families of tbe Craspedota. Tbe relations 

 which tbey exbibit to tbe Ctenopbora support tbe views of Haeckel and 

 Cbun. Tbe rarity of tbese forms may be partly explained by tbe sligbt 

 development of tbe gonads of tbe Medusa stage. And indeed sexual 

 reproduction in Eleniheria is quite inconsiderable as compared witb 

 multiplication by budding. 



Tbe following classification of tbe group is proposed : — 



Family Cladonemid^: Haeckel. 



C Elcutheiia. 

 First sub-family, Eleutherid.®, J Pteronema. 

 witb an apical cavity, \ Ctenaria. 



{ Dendronema. 



c'jip.-,^ ,( Cladonema. 



Second sub-family, Cladonemid^jJ 7 7 



sens. str. .No apical cavity, „ 



Tbey may be defined as baving the manubrium witb five edges, with 

 five perradial mouth-styles, and five perradial evaginations of the 

 gonads ; there are five radial canals, three of which divide, so that 

 eight canals of the second order open into the circular canal ; there are 

 eight tentacles. 



The manubrium of Cladonema has the form of a more or less well- 

 marked prism, the edges of which are perradial or lie in the planes of 

 the five radial canals of -the first order ; the central stomach may be 

 distinguished from a more well-developed oral tube ; the former alone 

 takes part in the development of the sexual products, and tbe stomach 

 is, as in the Codonidas, surrounded by a continuous gonad. Tbe five 

 edges of the manubrium correspond in position to five endodermal 

 longitudinal ridges which project into the lumen of the gastric cavity, 

 and leave between them five perradial grooves, which, at the proximal 

 end of the organ, pass into the five radial canals. 



The endoderm of the mouth -tube has some interesting histological 

 peculiarities ; at the mouth there are gland-cells consisting of finely 

 granular protoplasm, but, further in, the cells are almost all cnidoblasts ; 

 a large quantity of stinging cells, it may be observed, have also been 

 observed in the endoderm of the planula of Eleutheria. 



Cladonema is hermaphrodite, but the hermaphroditism is successive ; 

 at the same time there is no rule as to which several products shall first 

 appear. Several young egg-cells of considerable size may fuse into 

 one ; the gonads are always traversed by high supporting cells of the 

 ectoderm ; the spermatoblasts and tbe egg-cells, which are often found 

 lying among them, are only distinguished by their size. In the 

 endoderm of the gastric cavity there are to be found among tbe ordinary 

 nutrient cells deeply coloured bodies filled with more deeply coloured 

 spheres. Between the spheres it is often possible to make out distinct 

 cell-boundaries; tbese bodies have a close resemblance to germ-cells. 



* Zool. Anzeig., x. (1887) pp. 651-8. 



t Had the author followed the conventions of the British Association he would 

 have written Cladoneminaj, and so saved possibilities of confusion. 



