128 RITTER 



vient to the respiratory function, and the other to the alimentary 

 function. 



As to the contention that Ptychodera is Httoral in its habits 

 while Balcnoglossiis is abyssal ; and that these facts are to be 

 taken as evidence of the primitiveness of the latter, I will only 

 refer to what I have already said with reference to the mode of 

 life of Hm'j'imania maculosa : that it is not only a littoral spe- 

 cies, but that it is not a burrower ; and that both B. kiipfferi 

 and B. canadensis^ the species with which Harriniania is un- 

 doubtedly most closely related, are neither of them deep-sea 

 forms. 



In conclusion, I cannot refrain from calling attention to the 

 fact that Willey's arguments on this question are all advanced 

 in his preliminary communication, written while he was far away 

 from libraries and facilities for doing detailed morphological 

 work ; and that his completed memoir, written in England with 

 every facility at hand for exhaustive investigation, gives us 

 next to nothing, not only in extension of his former argument 

 on this question, but on the main question itself. 



After a careful study of both his papers, I can not escape the 

 feeling that the more careful study and maturer reflections from 

 which his later utterances came have not strengthened his earlier 

 views. 



This subject has received more attention than would have 

 been given it in a preliminary paper but for the fact that I 

 realize how much weight, and deservedly so, Willey's opinions 

 have in all portions of this field of zoology ; and I have thought 

 it important to set matters right here if possible before they 

 become fixed in a twisted condition. 



Spengel (1893) has given a list of the characters which he re- 

 gards as indicating the primitiveness of Balanoglossus as com- 

 pared with Ptychodera. Some of these — the ones I regard as 

 of most importance — are here enumerated, together with others 

 which are the results of my own studies. Those from Spengel 

 are as follows : 



1. The presence of synapticulai in the branchial skeleton of 

 Ptychodera and their absence in Balanoglossus. 



2. The presence of external liver lobes in the former and 

 their absence in the latter, 



