156 CEYLON PEARL OYSTER REPORT. 



Disk, 1 centim , deeply incised; spread, 10 centims. 



Locality: Stations I., II., and LVII. Twenty-two specimens, of which 12 were 

 from Station II. 



This species is closely allied to Antedon Lrevicuneala, Carp., Anlcdon similis, Carp., 

 and Antedon regalis, Carp. It differs, however, from each of them in having all 

 3 radials visible, a much smaller number of cirri, shorter arms, and carinate basal 

 joints on the lower pinnules. 



I have associated this species with the name of Mr. Robert Okell, B.A., F.L.S., 

 Hon. Secretary of the Isle of Man Sea-Fish Hatchery Committee, to whom I am 

 indebted for much kind help with the literature of the subject. 



Antedon reynaudi (Muller) Plate, figs. G to 12. 



As this species was very briefly described by Muller, and is still very imperfectly 

 known, I have thought it useful to give the following full description of the Ceylon 

 specimen, accompanied by the necessary figures. 



Description of an Individucd, Centro-dorsal a thick disk, with convex dorsal 

 surface, and bearing on its sloping sides, in two alternating rows, 25 cirri. Of these 

 all but a few immature ones are rather more than 2 centims. long, and have 35 or 

 36 joints, all of which are slightly wider than long, the later ones being laterally 

 compressed, and bearing, from the 14th onwards, a strong and forwardly directed 

 spine (Plate, fig. 8). 



First radials entirely concealed ; the 2nd just visible beneath the bases of the cirri, 

 and in almost complete contact laterally. Axillaries widely pentagonal, about half as 

 long again as the 2nd radials and without syzygy. Eighteen arms of about 200 short 

 and slightly overlapping joints (fig. 12). The 1st distichals are in almost complete 

 contact laterally, and form a slight tubercular elevation in their median line of 

 junction with the second. The first 8 brachials are discoid, the two 1st in almost 

 complete contact laterally, and are succeeded by about 30 shortly triangular joints. 

 These again are followed by discoid ones which continue to the tip of the arm. 



Two of the rays have each two series of 3 distichals (fig. 7), the axillaries having a 

 syzygy ; other two have each (fig. G) one series of 3 distichals, the axillaries having 

 a syzygy, and one series of brachials arising directly from the radial axillary. The 

 remaining ray has two series of 2 distichals, the axillaries having no syzygy. The 

 position of the brachials in which syzygies occur is very irregular, as shown by their 

 enumeration in 6 series, as follows: 



(I.) Brachials, 3, 12, I !>, 25, 33, 42, 50, 58, G6. 



(2.) 3, S, 12, 18, 25, 28, 35, 42, 55, 63, 67, 73, 80. 



(3.) 3, 14, 23, 31, 38. 



(4.) 3, 14, 23, 32, 46, 55. 



(5.) 3, 15, 21, 28, 34. 



(6.) 3, 6, 29. 



