﻿128 



PROCEEDINGS OF THE 



[April, 1857. 



young stage, when possessed of only eight tentacula, and measur- 

 ing onJy .08 in. alt. and .06 in. lat. At this stage it has somewhat 

 the form of Sarsia turricula, (pi. 8, fig. 6,) but its digestive trunk 

 is of an elongate conical form, reaching nearly down to the vail. 

 It resembles in form the trunk of Corynitis rather than that of 

 Sarsia. The mass of large cells occupies but a limited space, 

 about one-fourth the length of the trunk; is composed of few 

 cells, and is quite narrow, scarcely exceeding in width the 

 digestive portion of the trunk, which is slender, and rather re- 

 sembling the trunk of a young Sarsia, than that of an adult Turri- 

 topsis. The trunk ends in a bluntly pointed muzzle, well stocked 

 with thread-cells, which appears to constitute a single bunch. 

 One peculiarity which should also be noted in this young stage is, 

 that the transparent tissue of the upper portion of the disk, is, at 

 this time, prolonged for a short space downwards, so that the large- 

 celled transparent mass does not, at this time, abutt as it after- 

 wards does against the wall of the bell above, but is united with it 

 by a downwardly directed projection of the disk. This character 

 afterwards disappears, but we still see a trace of it in figure 1, a 

 more advanced specimen. Here the height of the bell is equalled 

 by its width, the cavity is very roomy, and the general form of 

 the animal approaches that of a sphere. The trunk has still its 

 conical form, but the single bunch of thread-cells at the mouth 

 now begins to divide itself into four; while the large-celled mass 

 above has increased, in extent and the number of its cells, and the 

 tentacula have reached the number of twelve. After this, the four 

 labial appendages grow out gradually, the digestive cavity in- 

 creases in size, the sexual organs begin to be developed, the large- 

 celled mass fills up gradually the space between it and the bell- 

 wall above, while the tentacula constantly increase in number. 

 It may as well be observed here, that the tentacula of the young 

 Turritopsis have a certain stiff appearance, which they afterwards 

 lose almost entirely. This remark is applicable to other genera, 

 as Corynitis, but not to Sarsia proper. 



Since writing the article on Turritopsis nutricula, and the de- 

 velopment of the medusan larva found in its bell (supra) I have 

 become fully sensible of the error of supposing that larva to have 

 been the young of Turritopsis, into which error I was misled by 

 the analogy of Tubularia. I cannot doubt that the larva in ques- 

 tion is the young of a Cunina, about to be described as an inhabi- 

 tant of our harbor, and that it passes its embryonic life for the 



