Notes on the morphology of the Tunicata. 535 



which was fixed and preserved in alcohol, does not take the stain so 

 well as material fixed in Perenyi's fluid or even in formalin, so that 

 I do not feel perfect confidence that there is no nerve cord in the 

 raphe. I have, however, failed to demonstrate one. I believe the 

 small gangliated cord that arises from the ganglion above the rapheal 

 duct is the rapheal nerve in a rudimentary condition. 



In both cross and sagittal sections through the intersiphonal or- 

 gans, one sees a great mass of nerve fibres {x in Fig. 54) which 

 arise from the anterior part of the ganglion and run down to the 

 duct of the gland, stopping at the point where the duct opens into 

 the ciliated funnel. In this region the basement membrane of the 

 epithelium of the duct is absent. I think it highly probable that 

 these fibres innervate the gland near the funnel. This recalls the 

 similar conditions in many Ascidians, e. g. Ciona and Herdmania. 



Herdman says in the third part of his report upon the Chal- 

 lenger Tunicata, p. 22: "The nerve ganglion is placed at the anterior 

 end of the branchial sac on the dorsal edge. It has a small pig- 

 mented sense-organ placed upon it"i). I have carefully 

 studied both dissections and sections of many individuals of all sizes, 

 but have failed to find a trace of any such organ. My material was 

 fixed and preserved in alcohol, so that any pigment, if present, would 

 not have been dissolved. This sense-organ of Pyrosoma has been 

 mentioned but never sufficiently described. Some one having the 

 proper material should study and describe it, that we may know what, 

 if any, relation it bears to the eye of Salpa. 



The condition of the intersiphonal organs in Pyrosoma supports 

 Herdman's opinion that Pyrosoma is derived from that group of the 

 compound Ascidians to which belong the families Diphsomidae and 

 Didemnidae. 



The Doliolidae. 



Doliolum affine Herdm. 



Plate 38, Figs. 55-57. 



Uljanin^) figures and clearly describes a structure which he 



calls the "Gehirnzapfen". It is evidently the neural gland. I copy 



his figure (Plate 38, Fig. 55) and quote his description of the organ 



in the sexual form of D. miilleri (p. 28): "Dieser Gehirnzapfen, von 



1) The emphasis is my own. 



2) Uljanin, 1884. See also Gbobben, 1882. 



