28 ZOOLOGY. 



CLASS III. GREGARINIDA (Gregarines). 



General Characters of Gregarinida. The largest and 

 "best known species of this group is an inmate of the 

 intestinal canal of the European lobster, and was named 

 by E. Van Beneden Greganna gigantea (Fig. 18). It 

 is worm-like, remarkably slender, and is sixteen mil- 



18 r~~ Cfre ff arin (f gigantea. L, two individual.-* of natural size K tne same 

 muei enlarged; , nucleus. A, the same encysted. B, subdivision of the cyst C. dM 

 ion of the contents of cyst into small sphoivs. observed in another gpecW jy the 

 spheres enlarged. M, cyst filled with i,seiilonavii-i-lla>. O.-After Lii'berkuhn D-F 

 tooner-Iike young of &. gigantta. G. II. pseudofllaria stage. 7, J, early nucleated 

 forms of Gregarina ffigantea.-After Vau Beneden. 



iimetres (over half an inch) in length, being the largest 

 one-celled animal known*. In this organism an external, 

 structureless, perfectly transparent membrane with a double 

 'contour can be distinguished. It represents the cell-wall 

 of the cells in the higher animals. Beneath this outer wall 

 is a continuous layer of contractile substance, forming a 

 true system of muscular fibrillae comparable to that of the 

 Infusoria. The body-cavity of the Gregarina contains a 

 * Excepting of course the larger Foraminiforu. 



