A Contribut. to the Embryol., Life-history, and Classificat. of the Dicyemids. 45 



(.004 mm — .009 mm). Towards the anterior limit of this tliird the 

 germ-cells became fewer aud smaller. 



The centrai porti on of the axial cell, between the two end portions 

 just described , was occupied only by three free nuclei , measuring 

 (1) .05 mm X 04 mm, (2) .03 mm X 02 mm , and (3) .04 mm X 

 .03 mm. Each nucleus contained a single nucleolus (from .0025 mm to 

 .005 mm), except one which had two very small nucleoli. 



One of the free nuclei was probably the paranucleus of the Infu- 

 sorigen; one was the centrai nucleus (.05 mm X .04 mm]; the remain- 

 ing two were the paranucleus and residuai nucleus of an Infusorigen 

 that once occupied the portion now filled with loose germ-cells. The 

 stili active Infusorigen is destined to leave another residuai nucleus, 

 and a tract of loose germ-cells like that seen in the opposite end of the 

 axial cell. Thus the lime would come when the entire axial cell would 

 he filled with germ-cells, and such cases are of frequent occurrence. 



6. D. moschatum, from Eledone moscliata^ Feb. 12. In this Ele- 

 done , the size of which was not recorded, not a single individuai was 

 found containing vermiform embryos, although the renai organ was 

 very thoroughly searched. Rhombogens and Transitionals were very 

 abundant, and several colonies of extremely long individuals were 

 found. Two cases may be described. 



a. A Transition al 5.55 mm long, filled with an enormous 

 number of germ-cells. No embryos nor embryonic stages, nor any trace 

 of an Infusorigen. Only 6 nuclei were seen, but I think one must bave 

 been overlooked. These nuclei were located as follows : 

 (1) 2.30 mm from the head; size .05 mm X 03 mm; no nucleolus. 



- - - - .025 mm; 1 nucleolus. 



- - - - .03 mm X 02 mm; 1 nucleolus. 



- - - - .03 - X .02 mm; 2 nucleoli. 



- - - - .045 - X 03 mm ; no nucleolus. 

 - - - .025 - X .02 mm ; 1 nucleolus. 



The nuclei were thus distributed aloug a centrai tract 1.35 mm long, or 

 about one fourth the entire length. In the bind portion, extending for- 

 ward to the 3*^ nucleus, the germ-cells were densely packed ; from the 

 3* to the 2*^ nucleus they became less numerous ; and between the 1^ 

 and P* nucleus only five were found. The anterior portion for about 

 1 mm is again densely packed with germ-cells, and from this point 

 backward to the P* nucleus the number rapidly diminishes. 



The germ-cells varied from .004 mm to .008 mm in diam. 



This individuai , judging from the contents of the axial cell , once 



