CEPHALOCHORDA. 217 



The oral cirri are long, and number about 30. They bear well-marked sense- 

 papillae. The " Raderorgan " is of the usual type, and has a median dorsal lobe and 

 two or three lateral lobes on each side. 



The notochord projects far in front of the anterior end of the myotomes and 

 projects posteriorly a little way beyond the last myotome. The dorsal tin ends 

 conterminously with the myotomes. The nervous system projects anteriorly beyond 

 the dorsal fin. A well-marked eye-spot is present. 



From the above description it will be noticed that this specimen agrees with 

 B. californiense in all particulars except in the arrangement of the myotomes. 



The total number of myotomes is the same in both, but the preatrioporal part is 

 shorter, and the postanal portion longer in ours than in B. californiense. The 

 geographical distribution may, at first sight, be supposed to be against this identifi- 

 cation, for the species is only recorded from San Diego Bay, California, and it is 

 certainly a noteworthy fact that it should turn up at the other extreme end of the 

 lndo-Pacific region. But it is not more remarkable than the case of Asymmetron 

 lucayanum, which was first found in the Atlantic and then in the Pacific Ocean. 



Our specimen differs from B. capense, as described by Gilchrist (9), in the number 

 and arrangement of the myotomes and in the presence of an eye-spot, which is 

 absent in B. capense. But variation has not yet been much studied in B. capense, 

 and possibly the full range of the myotomes is not known. It may be, therefore, 

 that this specimen, and those named B. capense, are only variations of B. califor- 

 niense, similar to those shown for other species in the tallies at the end of this report. 



The habitat of B. capense (Cape Colony) bridges the gap between California and 

 Ceylon, and it may be added that other species of Acraniates known from the 

 Maldive Archipelago have been found also at Zanzibar. 



It will be seen, therefore, that our Ceylon specimen differs but very slightly from 

 either B. californiense or B. capense. Both these forms are still comparatively little 

 known, and a re-examination of both is highly desirable, and would probably confirm 

 the view I have ventured to express, that these two species are not really distinct. 

 I believe I am justified in referring this specimen provisionally to B. californiense. 



Genus II. ASYMMETRON, Andrews. 



Left metapleuron stops just behind the anus, the right is continuous with the median 

 ventral fin ; gonads disposed in a single (right) series ; oral cirri with or without 

 sense-papilla?; intra-buccal tentacles 10 to 16; ventral fin with or without fin 

 chambers or rays; post-atrioporal cseca 1 to 2 in number. 



Asymmetron cingalense (Kirkaldy). Plate I., figs. 4-7. 

 Heteropleuron cingalense, KlRKALDY, 1895. 

 This species was represented by nineteen specimens found sporadically, like 

 B. lanceolatum, var. belcheri, in Foraminiferal sand in the Gulf of Manaar. 



2 F 



