148 Transactions of the 



and from this part a line is given off to surround the branchial 

 chamber, which subsequent information has induced me to think 

 must be part of the oesophageal nervous ring. The ciliated sac 

 mentioned by Professor Huxley and Dr. Moss was not visible in 

 this species. 



Only one granular spherical body is present near the endostyle, 

 instead of two, as is generally described. 



It is to be presumed that these specimens were quite young, for 

 the only structure which could by any possibility be referred to 

 the generative organs was a small granular mass attached to the 

 posterior wall of the body immediately behind the stomach ; this most 

 probably would be developed into a testis, as it occupies the position 

 ascribed to that organ by Professor Huxley, in A. jtahellum. 



The appendage is attached to the body by a broad base, the 

 central axis is distinctly articulated to the tunic, close to the dorsal 

 border of the stomach, so that the idea entertained by Professor 

 Gegenbaur that this was a hollow vessel communicating with the 

 fluids of the body is untenable ; the central axis terminates distally 

 in a i^oint at a short distance from the end of the tail ; two fibres 

 of striated muscular fibres are situated in front of and two behind 

 the rod, and one on each side ; they gradually taper to a point, and, 

 extending beyond the end of the axis, terminate close to the distal 

 extremity of the appendage ; they are striated as far as their termi- 

 nation. The rest of the appendage is formed of an expansion of a 

 diaphanous material, resembling that which constitutes the tunic of 

 the animal ; the posterior border was always found turned down at 

 the proximal end. After being some time under examination this 

 part of the appendage develops irregular, longitudinal, and trans- 

 verse markings, which, however, do not appear to me to be any- 

 thing more than a crumpling of the external membrane, and nothing 

 resembling a layer of epithelium was to be seen. 



Since reading this paper I have had an opportunity, through 

 the Idndness of Mr. Stewart, of consulting an extremely interesting 

 monograph by Dr. Hermann Fob* The author divides this family 

 into three genera, viz. Oikopleura, Frittillaria, and Kowalewskaia. 

 The long-bodied form that I have described belongs to the genus 

 Frittillaria, in which Dr. Fol makes five species ; from all these my 

 specimens differ in the shape of the body and tail, in possessing 

 smooth muscular fibres, in the direct communication of the stomach 

 with the rectum, in the presence of a pyriform body, and in being 

 much smaller. 



The short-bodied form belougs to Dr. Fol's genus Oikopleura, 

 of which he hkewise describes five species ; from all of which my 

 specimens also differ in the shape of the stomach, intestines, and 



* ' Etudes sur ]es Appcndiculaiies,' reprinted from tlie 'Mem. dc la Soeie'to de 

 riiys. ct d'Histoirc Nat. de Geaeve,' toiii. xxi., 2"'^ partie. 



