HARRIMANIA MACULOSA 1 27 



about its meaning, it seems to me that at least as strong a case 

 can be made for the supposition as against it, that the condition 

 is the result of secondary modification from the more tj^pical en- 

 teropneustic arrangement. Willey's observations relative to the 

 closing'over and mucous fusion of the genital pleurae at their 

 free edges to produce a transient atrial chamber in this species, 

 and his reflections upon the possible significance of the facts, 

 are exceedingly interesting. Holding as he does, that the gen- 

 ital pleurae are primitive structures, he is, of course, justified in 

 assuminsf that in case there is a causal relation between them 

 and the peculiarities of the pharynx, the two have developed 

 pari ^assu, and hence that the one is as old as the other. On 

 the other hand, granting such a relation between the two, if one 

 holds as I do, following Spengel, that the pleurce are secondary 

 acquisitions, then it might follow likewise that the peculiarity 

 of the pharynx is secondary. But I doubt if there is yet suffi- 

 cient evidence at hand to warrant a positive opinion one way or 

 the other. I may add, for what it is worth, that in my new species 

 DolichoglossiLS mtermedms, in which the outline of the body in 

 the pharyngeal region is less broken by genital ridges and bran- 

 chial grooves than in any other known Enteropneust, the gill 

 orifices are more elongated transversely and more laterally 

 directed than in any species except PtycJwdera of the jiava 

 type. 



As to Willey's third point, that the absence of division of the 

 anterior region of the alimentary canal into branchial and esoph- 

 ageal portions in the Balanoglossidee " militates strongly against 

 their being regarded as more primitive than P/y(:/z<9<i^r«" (p. 180), 

 I must confess that I fail to catch the author's idea ; and in the ab- 

 sence of an explanation as to how the facts militate in this way, I 

 must hold to the orthodox method of interpreting such conditions, 

 and regard the divided as contrasted with the non-divided state 

 as more highly differentiated, and hence as pointing to a more 

 instead of a less primitive nature of the animals under consid- 

 eration. It seems to me that we have here only another in- 

 stance of a common occurrence in theh Cordata, namely, a ten- 

 dency of an original simple, unmodified section of the enteron 

 to become differentiated into two distinct parts, the one subser- 

 Proc. Wash. Acad. Sci,, August, 1900. 



