GONTMARETIA TYLOTA. 243 



terminal one. The valves of these pedicellariae are for the most part widely 

 open, in the preserved specimens, lying about horizontal with reference to the 

 vertical stalk. They are .40-.50 mm. long, very flat and narrow and terminate 

 in two sharp, slightly diverging teeth; the general apper ranee is much like the 

 valves in Lovenia elongata as figured by Koehler (1914. Ech. Indian Mus. Spat., 

 pi. 19, fig. 26). The stalks and most of each valve in these curious pedicellariae 

 are cream-color or nearly white, but the tip of each valve is encased in deep 

 purplish or bluish black glandular tissue giving the open pedicellaria an odd 

 appearance. 



Besides these globiferous pedicellariae, ophicephalous, tridentate, rostrate, 

 and triphyllous also occur. The triphyllous are quite common but are very 

 small; the valves are only about .07 mm. long, and the blade is less than .05 mm. 

 wide. The ophicephalous are rather rare, and notable for remarkably long and 

 narrow valves, which are about .20 mm. long, with the blade narrowly oval, 

 about .06-07 mm. wide and the base .10 mm. across. The tridentate and 

 rostrate seem to intergrade and it might be better to call them all tridentate. 

 But I have reserved the name rostrate for the small form, with valves .15-.30 

 mm. long, distinctly curved and meeting only at tip, and with a rather wide 

 blade which is not noticeably compressed. The tridentate proper are of two 

 kinds, the stout and the slender. The stout have the valves .40-.80 mm. long 

 and the blade one eighth to one fifth as much in width; the blade is strongly 

 compressed especially near base so that its depth is nearly equal to its width. 

 The slender tridentate have the valves .45-. 75 mm. long; the blade, however, 

 is exceedingly narrow, its width, even near tip, where widest, only one four- 

 teenth to one tenth as great as its length, while its depth may actually exceed 

 its width; in a valve not quite .75 mm. long, the base is .10 mm. wide, the blade 

 .10-. 15 mm, from tip is .05-06 mm. wide and about .04 mm. deep, while at its 

 base the blade is only .02 mm. wide but is .06 mm. deep. The margins of the 

 blade in both kinds of tridentate pedicellariae are finely but conspicuously 

 serrate. It is chiefly on and about the periproct, and on the subanal plastron 

 that tridentate pedicellariae occur. 



This interesting species is undoubtedly near to Pseudomaretia alia in many 

 ways, but the character of the periproct as well as that of the sternum prevents 

 placing it in the same genus. The important difference between the sterna 

 of Gonimaretia and the nearly allied genus Lovenia is well brought out by 

 comparing the figures, PI. 161, fig. 5 and PL 160, fig. 7. There is no doubt that 

 Gonimaretia, Lovenia, Pseudomaretia, Pseudolovenia, and Maretia constitute 



