344 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



hundreds of normal larvae, with ciliated bands and vestibulary invagination. A number of embryos 

 were still enclosed within the egg membrane; it seemed clear that they had considerable difficulty in 

 getting out of the shell in the still water in the dish, as I have formerly found it to be in the case with 

 Antedon petasus. I then put these embryos into a plankton net in the tank, under the tap, so as to 

 have them in constant movement in the water, and in this way I succeeded in getting another good 

 lot of free-swimming embryos. 



All the embryos were then put into some dishes with the bottom covered by small pieces of 

 broken shells and corals, to which I hoped to see them attach themselves. Not till the 25th, thus 

 after 5-6 days free-swimming, did I find a few of them attached and having assumed the Penta- 

 crinoid shape, all the rest of the larvae still swimming, and no more of them did attach themselves. 

 In the course of the following five days a few larvae tried to attach themselves to the bottom of 

 the dish, but without success, and in 2-3 days more all of them had disappeared. Evidently the 

 difficulty with these Crinoid larvae is to find suitable objects for them to attach themselves to, as 

 I found to be the case with Tropiometra carinata. 



Having already studied the embryological development of Tropiometra carinata in detail, I did 

 not preserve any of the larvae for sectioning, wanting to have as much material as possible for 

 eventually studying the further postembryonal development of the Pentacrinoids. I expected that 

 by means of the various cultures of food organisms that I had at disposal it would be easy enough 

 to keep the Pentacrinoids growing in the dishes. Unfortunately, this did not prove successful. 

 Repeated attempts to get new cultures of the larvae failed; evidently the breeding season had 

 passed at least no more eggs were got. Thus the information I can give of the development of 

 this Tropiometra is confined to the above statements, and to the figures of the young Pentacrinoid. 



This Pentacrinoid has much resemblance with that of Tropiometra carinata. The oralia have 

 no outturned edge such as is found in the Pentacrinoids of the Antedonids. There are three well 

 developed infrabasals. The anal plate has appeared, but there is no trace of the radial and neither 

 have I found the spicules of the tentacles or the first sacculus in any of the Pentacrinoids, though 

 kept alive till the age of three weeks. It may, however, be mentioned that as in Tropiometra 

 carinata I have found in one specimen a small, young plate lying some distance out in the primary 

 tentacle. It may be suggested that it is the first axillary; but in the absence of further develop- 

 ment stages this remains a little uncertain. 



Localities. Suez [Moseley, 1877; MacMunn, 1890; Newbigin, 1898; A. H. Clark, 

 1911, 1912]. 



Ras-el-Millan, Gulf of Suez; Dr. Robert Hartmeyer [A. H. Clark, 1912] (1, Berl. 

 Mus., 5603). 



Erg Tor, Gulf of Suez; Dr. Robert Hartmeyer [A. H. Clark, 1912 (as Eig Tor); 

 Hartmeyer, 1916] (1, Berl. Mus., 5602). 



Tor, Gulf of Suez [A. H. Clark, 1912]. 



Red Sea (probably Suez) [Audouin, 1817; A. H. Clark, 1909, 1911, 1912]. 



Ghardaqa, Red Sea [Mortensen, 1937]. 



Red Sea [von Martens, 1869; A. H. Clark, 1911, 1912, 1914]. 



Red Sea [P. H. Carpenter, 1881, 1888; de Loriol, 1893; A. H. Clark, 1911, 1912, 

 1914; Hartlaub, 1912]. 



Aden; Prof. Johannes M tiller [P. H. Carpenter, 1881, 1888; de Loriol, 1893; 

 Hartlaub, 1912; A. H. Clark, 1911, 1912] (1, Berl. Mus.). 



Muscat [P. H. Carpenter, 1888; Hartlaub, 1912; A. H. Clark, 1912]. 



Geographical range. The Red Sea and eastward to Muscat. 



Bathymetrical range. Littoral. 



History. In 1817 Jean Victor Audouin published in Savigny's "Description de 

 1'Egypte" a figure of a comatulid identified only as Comatula sp., that undoubtedly 

 represents this form. It was first definitely recorded from the Red Sea by Prof. 

 Edouard von Martens as Comatula carinata in 1869. 



