Packard.] ^Oo [jan. 16, 



really be considered as true verbs. Then we must try to clear 

 them of all the artificial additions of the priests, and to find out 

 the real Indian verb and all its possible forms, tenses and moods, 

 a task by no means so easy as it would seem from a superficial 

 examination. In a subsequent publication, I propose to enter 

 more fully upon this theme. 



On the Embryology of Limulus polyphemus. III. By A. S. Packard. 

 (Mead before the American Philosophical Society, January 16, 1885.) 



The stage under examination is that represented on figs. 13 and 13, 14 

 and 15 (Plates iii and iv), of my essay on the development of Limulus, 

 Memoirs Boston Society Natural History, 1872. At this stage the oval blas- 

 todermic disc, with the six pairs of the cephalic appendages, is distinctly 

 formed ; the mouth is seen in a position in front of the first pair of append- 

 ages, and from it the primitive streak passes hack to the posterior margin 

 of the blastodermic disc or "ventral plate." The abdomen is separated 

 from the head by a curved groove, as seen in fig. 12, of my memoir. 



I should here remark that the eggs were not fresh, but selected from a 

 number kindly collected for me in 1871, by Rev. Samuel Lockwood, and 

 since then preserved in alcohol, which had been renewed several times, 

 my studies on the embryology of this animal having been interrupted 

 from year to year, in hopes of obtaining fresh eggs, and for want of good 

 thin sections of those I already had. I finally applied to my friend Dr. C, 

 O. Whitman, whose great experience in making delicate sections was 

 kindly placed at my disposal ; the sections examined were actually made 

 by Mrs. Whitman, under the direction of her husband. The period ex- 

 amined is an interesting one, as while the cephalic appendages were well- 

 developed, the abdominal appendages were not as yet indicated, nor the 

 post-oral nervous ganglia. 



The first point, which at once excited my attention, was the nature of the 

 embryonic membrane which I had previously regarded as the homologue 

 of the amnion, and afterwards as the serous membrane of insects, but which 

 Mr. J. S. Kingsley* has found to be secreted from the blastoderm. That 

 he was correct, and that I was in error in regarding it as truly cellular, was 

 at once seen to be evident. A thin section (fig. 1 and 5), shows that the 

 membrane is very thick, structureless, the cellular appearance being con- 

 fined to the external surface. This membrane is evidently secreted by the 

 blastoderm ; the irregular cell-like markings (see my second memoir, 1880, 

 PI. iii, figs. 14, 14a, 14c, 14cZ), are, so to speak, casts of the blastoderm cells, 

 which with the marks of even their nuclei are impressed upon the 



* The Development of Limulus, Science Record, ii, pp. 249-251, Sept., 1884. 



