380 ON THE ANATOJIY OF A SUPPOSED NEW SPECIES OF COENOPSAMMIA. 



Fig. 21. Transverse section through a portion of a longitudinal retractor muscle of a 

 primary mesentery. The structureless membrane is drawn out into simple or branched 

 lamelliform folds, on which the somewhat rectangular or rounded fibres are placed. 



Fig. 22. Transverse section through a primary and a secondary mesentery at a slightly 

 lower level to that represented in the left half of sextant F in Figure I. The coelenteron is 

 almost obliterated. The tertiary mesenteries {in. 3) are recognisable as fine bands. Neithei- 

 the primary nor secondary mesenteries have any trace of muscular bands but in the 

 structureless membrane of each an ovum is situated. Round these the endoderm is much 

 thickened ; its nuclei are generally indistinct but towards the free surface it is crowded with 

 fine granules. Over the structureless membrane a few larger granules are found and can be 

 seen in every stage of their passage into the ova, where they form a row of granules round 

 the periphery. The nucleus of the ovum is large with large nucleolus : no nuclear membrane 

 however is generally \'isible. 



Zoological Laeoratort, 

 January 31, 1899. 



