NO. 1989. ASCIDIAN8 FROM NORTHEASTERN PACIFIC— RITTER. 457 



But valuable as Hartmeyer's studies of these animals are, I can not 

 but think he has taken a backward step in proposing to suppress the 

 genus name BoUenia (Hartmeyer, 1909), page 336, and to transfer all 

 the species to Halocynthia (Pyura) . His low valuation of the presence 

 or absence of the peduncle as a generic mark undoubtedly has much 

 justification, though it would be interesting to see what would 

 result were the argument employed by him in this connection to be 

 rigorously applied throughout the whole of zoology and botany. 

 Without doubt a considerable percentage of all the genera now recog- 

 nized would be set aside. But assuming that the mere presence of the 

 peduncle is not sufficient to save Boltenia, there remains the dis- 

 tinctive position of the branchial orifice in relation to the insertion of 

 the peduncle. Hartmeyer considers this also of little importance, 

 instancing in support of his view the fact that in some genera, as 

 Molgula {M. crystallina) , the position of the orifices relative to the 

 peduncle is similar to that in BoUenia and Halocynthia. That is, he 

 points out a transition of character not between these two genera but 

 between Boltenia and some other genus. This way of treating 

 resemblances and differences between groups of organisms certainly 

 would play havoc with our classifications if consistently carried out. 

 Much depends on one's views as to what characters are superficial 

 and what are fundamental. As I observe and think about organic 

 structure, I am unable to see that organs and parts located on the 

 surface and so observable without dissection are necessarily super- 

 ficial in a biological or logical sense; nor contrariwise is the internal 

 position of a part the essence of fundamentality. Ought it to be 

 assumed, for example, that the digestive tract, because internally 

 located and hence literally a fundamental anatomical organ, is there- 

 fore more constant and hence more reliable for grouping animals than 

 is the peduncle ? Not necessarily. It is, if observation proves it to 

 be so; not otherwise. As a matter of fact, I believe it would be 

 quite as difficult to prove that the peduncle present here and there 

 among ascidians is any more adaptive than is the branchial sac, the 

 intestine, or the renal organs. Renal organs are present in some 

 groups of ascidians, but not in others. Are they fundamental ana- 

 tomical parts or not ? When one compares an intestine as volumi- 

 nous and elaborate as that of Styela macrenteron (see p. 466) with 

 one so diminutive and simple as that of Styela thelyphanes Sluiter, 

 1904, page 68, he can hardly be impressed with the constancy of this 

 anatomical organ. 



The collection contains many specimens of many sizes, so that my 

 conclusicins rest on rather ample observations, so far as north Pacific 

 representatives of the species are concerned. 



The accompanying table (Table 9) exhibits something of the range 

 of variation of the species. 



