212 CEYLON PEARL OYSTER REPORT. 



Ceylon specimens they ended together. The "Raderorgan" is well developed in 

 these specimens, and has a median dorsal lohe and five or six large lateral lohes on 

 each side. In one specimen examined one of the lateral lobes was branched. 



No. IV., Table L, showed an unusual dark oval patch anterior to the dorsal fin 

 and just dorsal to the notochord (fig. 2). No structure could be made out, but when 

 cleared up in clove oil the dark patch was found to have a ventral extension on the 

 left side. Unfortunately the specimen had not been preserved specially for 

 histological work, and so the sections that were made showed no additional structure, 

 the only appearance being a large patch dorsally and to the left side of the notochord, 

 which stained deeply with hematoxylin. 



Branchiostoma lanceolatum, var. belcheri, Gray. Plate L, fig. 3. 



Branchiostoma belcheri, Gray, 1847, and others. 

 Amphioxus belcheri, Kirkaldy. 



This variety, which is usually regarded as a distinct species, formed the greater 

 part of the collection, being a total of 58 specimens out of 98. It has only been 

 previously recorded from the neighbourhood of Ceylon by Thurston* in 1890, who 

 mentions the species being dredged 30 miles south of Madras in 1887-88 ; in fact it 

 has been found but sparingly anywhere before. This large collection, therefore, has 

 offered opportunity for a closer examination of this form, which, I think, has shown 

 that we cannot any longer regard it as specifically distinct from B. lanceolatum. 

 This matter is dealt with in detail in my recent paper in the ' Transactions of the 

 Liverpool Biological Society,' where I have given tables compiled from the observations 

 of different workers, showing how the characters of the one form fade gradually into 

 those of the other. 



The Ceylon specimens were found in the following localities : 



(1.) Ten miles north of Cheval Paar, June 3rd, 1902, 7| fathoms. Seven 



specimens. 

 (2.) Outside Karativo Paar (Stn. LVIIL), March 10th, 10 fathoms. Two 



specimens. 

 (3.) Oft* Karkopani (Stn. IV.), February 2nd, 8 fathoms. Two specimens. 

 (4.) Off Mutwal Island (Stn. LXVIL), March 19th, 14 fathoms. Three specimens. 

 (5.) Periya Paar Kerrai (Stn. L.), 7^ fathoms, sand, March 4th. Four specimens. 

 (6.) Off Chilaw Paar (Stn. LXIX.), 10 fathoms, March 20th. Six specimens. 

 (7.) West Cheval Paar (Stn. LXV), March 18th, 7\ fathoms. Nine specimens. 

 (8.) Near Periya Paar (Stn. LXIL), March 13th, in Foraininiferal sand, 



11 fathoms. Eleven specimens. 

 (9.) South-west of Cheval Paar (Stn. XLIX.), March 1st, 8| fathoms. Fourteen 



specimens. 



* Madras Government Museum, Bulletin No. 1, p. 26. 



