218 CEYLON PEARL OYSTEE REPORT. 



The colour of this species had practically the same range as the others deep 

 orange, purplish-pink, and pale fawn tints being found. The dimensions of the 

 specimens are recorded in Table III. The total length varied from 20 to 36 millims., 

 the average being 26 '5 millims. 



The specimens were found in the following localities : 



(1.) Half a mile East of Dutch Modragam Paar (Stn. LVL), March 10th, 



8 fathoms. Two specimens. 

 (2.) South of Adam's Bridge (Stn. LTV.), March 8th, 8 fathoms. One specimen. 

 (3.) Off Karkopani (Stn. TV.), February 2nd, 8 fathoms. One specimen. 

 (4.) Between the Cheval Paars (Stn. XLVIIL), March 4th, 7^ fathoms. One 



specimen. 

 (5.) South-west of Cheval Paar (Stn. XLIX.), March 1st, 8 fathoms. Two 



specimens. 

 (6.) West of Periya Paar (Stn. XVII.), February 4th, 11 fathoms. Eight 



specimens. 

 (7.) West of Periya Paar (Stn. LXT.)., March 12th, 12 fathoms. Four specimens. 



Although so small compared with the specimens of the form B. belcheri, nearly all 

 were sexually mature thus showing that the average length of the adult 

 A. cingalense is much smaller than that of the adult B. belcheri. 



Of the nineteen specimens, ten were males and seven were females, while the sex 

 of two could not be determined. The number of gonads varied from 18 to 26, always 

 on the right side, the average being 24. 



The total number of myotomes varied between 61 and 64, 63 being the average 

 and most frequent number. The most common myotome formula was 39, 16, 8, which 

 occurred 10 times out of 19 specimens. The preatrioporal myotomes varied between 

 37-39, the preanal between 15 and 17. and the postanal between 6 and 8. This 

 species thus has a comparatively short postanal portion. 



The variation in the total number of the myotomes and in their arrangement is 

 less in this species than in any other species of the group. The fins are fairly 

 constant throughout the specimens (figs. 4 and 6), and agree well with Kirkaldy's 

 figures (6). The dorsal fin is deeper anteriorly than in the rest of its extent, 

 recalling in a lesser degree the condition of A. cultellum (Peters). It has fin 

 chambers with single fin rays. The dorsal fin in all cases overlaps the nervous 

 system. The ventral fin is very shallow and has fin chambers with double fin rays 

 which are very small and difficult to see. The ventral fin chambers are not prolonged 

 postanally. 



In only one of the 19 specimens is the relation of the dorsal fin to the anterior end 

 of the notochord as figured by Kirkaldy. In that figure the anterior end of the 

 notochord is but a little way in front of the anterior end of the dorsal fin. This is 

 seen in but one of the Ceylon specimens, No. X., Table III. (see fig. 5). In the 



