THE PELAGIC TUNICATA. 209 



witli tlie pharynx through a common small orifice. We mean only that, 

 examined in toto. the presence of these coeca is not recognizable in our 

 specimens. 



Although Huxley's work on Appendicularia is so admirable from the 

 point of view of general morphology, many of the details, upon which the 

 present-day characterization of species and genera rests, he touched very 

 meagrely or not at all. For example, the glanduhxr areas by which the 

 "House" is secreted, the "oikoplast" epithelia of Lohmann, he knew noth- 

 ing about. In fact his studies on Appendicularia jlagellmn were made with- 

 out his coming in contact with the "house" at all. Likewise his description 

 of the intestinal tract is rather too meagre to satisfy the importance that 

 this structui-e has assumed for purposes of classification at the hands of 

 recent students of the group. 



These deficiencies in Huxley's description and the incompleteness of our 

 own data render the identification of the two forms as one and the same 

 somewhat less certain than could be wished ; nevertheless it is, we believe, 

 justified by the following readily recognizable similarities : The two are 

 essentially of the same size and dimensions (compare the measurements of 

 our specimens given above with the size diagram inarked " N. S." in Hux- 

 ley's PI. XVIH). This fact will be seen to have special importance when 

 attention is called to the further fact that the length of the tail in this 

 sjaecies is nearly three times that of tlie next lai'gest species of the genus 

 excepting 0. coplwccrcci, which it just about equals. 



The general outline of the body (compare fig. 9 with Huxley's PI. XVHI, 

 fig. 1, and fig. 2) of the two forms is essentiall}' the same, and would seem 

 to be rather sharply differentiated from most other species by the relatively 

 large diameter of the anterior end to accommodate the unusually large 

 branchial orifice, or mouth. The great lens-th of the rectum and the far 

 forward position of the anus in both forms is another apparentl}' common 

 characteristic. 



Again, the tails agree in being narrowly pointed at the posterior end in 

 both forms, and while this is not an exclusive character, the tails of so many 

 of the other species of the genus are of some other form that considerable 



weight attaches to this similarity. 



u 



