508 27*6 American Naturalist. [June, 



and the fourth pair in the third segment. In addition to these the first 

 pair of mesodermal pouches, right and left of the first pair of append- 

 ages divide and give rise to a pair of head pouches. The gonad 

 develops as a dorsal evagination of the archenteron between the second 

 and third segments and later pushes itself forward into the region of 

 the second segment. 



There develops further, in the region between the stomach and mid- 

 gut an unpaired accessory sexual gland and at the same stage there is 

 developed a larger pair of evaginations of the midgut which the author 

 designates as the midgut glands. The salivary glands develop as ecto- 

 dermal invaginations of the head segment. The author does not con- 

 sider the musculature, the nerves, or the transformation of the coelomic 

 pouches, reserving those points for another paper. 



After a careful consideration of historical and comparative points, 

 in which he discusses the results and views of the various authors who 

 have published papers on the tardigrades and presents his own ideas on 

 the questions concerned, the author, in closing, hopes that what he has 

 contributed to a knowledge of the morphology of the tardigrades will 

 be sufficient to give them a place at the bottom of the arthropod stem. 

 He does not maintain that the tardigrades represent the stem form of 

 the arthropods but that they have branched off early and at the very 

 bottom of the arthropod phylum and in many respects developed 

 partially, but a considerable number of primitive characters remain 

 which seem to show that they are transitional forms to other phyla. 



In a second paper by the same author 3 the earlier embryonic stages 

 of Murmb'mtti* HHu.'fomjx Duj. are described as follows. 



Contrary to condition found in the terrestrial tardigrades, in the 

 species studied, the males are equal to the females in number. The 

 males are smaller by half than the females, the latter appearing brown- 

 ish-yellow in color owing to the eggs in the ovary which in a ripe con- 

 dition attains a considerable size. The author was unable to distinguish 

 a copulatory apparatus as described by Graff and the manner of 

 fertilization precludes the existence of such an organ. The female 

 withdraws her body into the chitinous envelope so that the hinder part 

 is clear as far as the second pair of appendages and the eggs are 

 extruded into this cavity through the anus. The hinder end of the 

 chitinous shell of the female is turned in for a short distance, forming 

 a short tube. 



During copulation the female moves about dragging the male cling- 

 ing to her back. The male deposits the spermatazoa near the posterior 

 3 Biologkches Centralblatt. , 15. 



