210 CEYLON PEARL OYSTER REPORT. 



the species B. belcheri. Thus, at most, three species, represented by six specimens, 

 were then known from Ceylon ; and during the course of Miss Kirkaldy's work 

 she received four more specimens from Ceylon which proved to he A. cine/ale use. 



The present collection, therefore, is by far the largest yet made known from Ceylon. 

 The species include Branchiostoma lanceolatum, B. lanceolatum, var. belcheri, 

 Asymmetron (Heteropleuron) cingalense, Asymmetron (Heteropleuron) cultellum, 

 Branchiostoma (Dolichorhynchus) indicum, Branchiostoma pelagicum (the six tow-net 

 specimens), and B. californicnse (?). 



The specimens were preserved, some in alcohol and others in formol, and the latter 

 were in a most excellent state of preservation, being rendered slightly transparent, 

 while the exact outlines and shapes of the fins were splendidly maintained. The 

 spirit specimens were not nearly so good, so far as regards the external appearance, 

 although better in some respects for histological examination. 



The group Cephalochorda has a single family, Branchiostomatidae, containing two 

 genera, Branchiostoma and Asymmetron. In discussing the Ceylon species, I shall 

 follow the classification and nomenclature given in my recent paper published by the 

 Liverpool Biological Society (10). 



Genus I. BRANCHIOSTOMA, Costa. 



Metapleural folds end symmetrically just behind the anus, separated by the ventral 

 fin ; gonads disposed in two lateral series ; ventral fin with fin chambers which 

 may or may not have fin rays ; oral cirri when present have sense-papillae ; 

 atrial chamber prolonged behind the atriopore in a single (right) caecum. 



Branchiostoma lanceolatum (Pallas) Plate I., figs. 1,2. 



Limax lanceolatus, Pallas, 1776. 

 Branchiostoma lubricum, Costa, 1834 and 1813. 

 Amphioxus lanceolatus, Yakrell, 1836, and others. 

 Branchiostoma lanceolatum, Gray, 1851, and others. 



This species, which has only before been doubtfully recorded from Ceylon 

 (Andrews (3)), was represented by ten specimens in the collection. 

 They were from the following localities : 



(1.) Galle (Stn. XXXV.), February 14th, 7 fathoms. Two specimens. 



(2.) Ten miles North of Cheval Paar (Stn. LIIL), March 6th, 7h fathoms. Three 



specimens. 

 (3.) Periya Paar Kerrai (Stn. LIU.), March 4th, 7^ fathoms. One specimen. 

 (4.) Off Watering Point, GaUe (Stn. XXXVIIL), February 17th, 9 fathoms. 



Four specimens. 



The various measurements of these ten specimens will be found in Table I. at the 



