No. 501] 



NOTES AND LITERATURE 



on a thoroughgoing examination of everything in the make-up 

 of the animals, thanks particularly to the standard set by 

 Spengel's splendid monograph of 1893. From this circum- 

 stance it follows that anatomical studies on the adults of either 

 old or new species are not likely to yield greatly important new 

 facts. A few points of considerable general interest, however, 

 come from recent work. 



The superficial, presumably secondary, metamerism of por- 

 tions of the body in several species has attracted the attention 

 of most observers. Willey and Spengel have given it special 

 consideration. In no known species is this more strikingly seen, 

 perhaps, than in the Neapolitan one lately described by Spengel. 

 The prominence and regularity of the bilaterally arranged cross- 

 welts or ridges on the ventral side of the genital region as 

 figured by him, are remarkable indeed. It is not likely that 

 these structures have any great significance either phylogenetic 

 or physiological. They are probably in the main growth char- 

 acters and are interesting on just this account. 



In his extensive studies on the excretory organs of annelids 

 and amphioxus some years ago, E. S. Goodrich predicted that a 

 peculiar type of cells observed in these animals and called by 

 him Solenocytes, would on special search be found in the Enter- 

 opneusta. Spengel lias <rivon attention to this point, with nega- 

 tive results so far. (Beitrag III.) 



References may here be made to Spengel's tilts with Arthur 

 Willey on the latter 's speculations as to the vertebrate homol- 

 ogies of various Enteropneust organs. For example, Spengel 

 examines with his accustomed thoroughness the dorsal nerve 

 roots of the collar region in several species and treats with quite 

 pungent sarcasm Willey 's contention that in these we have the 

 homologues of the vertebrate epiphysis. A fragment of this 

 particular tilt is worth repeating as literature, though it may be 

 questioned whether Willey ever took liinis. lt' s.-rionsly enough in 

 much of his theorizing on these matters to warrant giving his 

 utterances much time under the aegis of real science. "An 

 epiphyseal structure," Willey is quoted as saying, "like an 

 enteropneustic root, can be transformed into an epiphyseal 

 structure like a pineal eye by losing its primary function . . . 

 passing through a condition of pigmentose degeneration 

 and then being rejuvenated by the acquisition of a new func- 

 tion." Then Spengel himself, "wo in aller Welt giebt es eine 



