CLARK: BRITTLE-STARS. 287 



Amphiodia MESOPOMA. 



Plate 3, fig. 7. 



H. L. Clark, 1915. Mem. M. C. Z., 25, p. 247, pi. 6, fig. 11-14. 



Among the brittle-stars collected in 1915, at Westernport, Victoria, 

 by Mr. J. Gabriel are a number of specimens which I believe represent 

 this species. At any rate I cannot find any tangible character by 

 which they may be distinguished. It is certainly extraordinary that 

 a species the unique holotype of which was collected in Torres Strait, 

 should be found at Westernport but comparison of the specimens has 

 satisfied me that such is the case. This comparison has moreover 

 revealed an unfortunate mistake in the original description. The 

 broken arms which were supposed to be the arms of A. mesopoma, 

 and figured as such (pi. 6, fig. 12, 14), now prove to belong to some 

 other amphiuran (probably Amphioplus parviclypcus). The holo- 

 type of A. mesopoma broke off all of its arms autotomously soon after 

 it was collected and as specimens of A. parviclypcus were in the same 

 pail, it is not difficult to see how the confusion occurred. The speci- 

 mens from Westernport are smaller than the Torres Strait specimen, 

 but not very much so, and have some of the arms nearly intact. 

 They show that the upper arm-plates in A. mesopoma are only about 

 twice as wide as long, are considerably narrower proximally than 

 distally and do not have the distal corners noticeably rounded. In 

 view of these differences the true shape of the upper arm-plates in 

 A. mesopoma is shown (Plate 3, fig. 7). 



Amphiodia planispina. 



Amphiura planispina von Martens, 1867. Monatsb. K. Preuss. akad. wiss. 



Berlin, p. 347. 

 Amphiodia planispina VerriU, 1899. Trans. Conn, acad., 10, p. 313. 



After considerable hesitation, I refer to this Brazilian species, a 

 very fine Amphiodia dug out of the mud and eel-grass roots on the 

 southeast side of Loggerhead Key, Dry Tortugas, June 21, 1917. The 

 disk is nearly 10 mm. across and the arms are about 70 mm. long. So 

 far as the oral surface and the arms are concerned the specimen is 

 readily referred to A. jilanispina, but the arm-spines are less flattened, 

 the disk-scaling is less coarse and the radial shields are less nearly 



