648 



SCIENCE. 



[N. S. Vol. I. No. 24. 



These have been simply distinguished by 

 Mr. Willey by the number of myotomes, 

 but most of them may be distinguished by 

 other characters. Of the ten s]3ecies, five 

 belong to Br anchiostoma, two to Paramphioxus, 

 one to Epigonichthys, one to Asymmetron, and 

 one to Anvphioxides. 



What are specific characters in any Bran- 

 chiostomoid genus is a question as yet un- 

 determined. The only one that has been 

 generally used (exclusive of what are 

 rather of generic importance) is the number 

 of myotomes as a whole and in diiferent 

 regions. Even such a character has not 

 been constantly adhered to. For example, 

 in Dr. E. A. Andrews' useful and able 

 memoir on ' An TJndescribed Acraniate' 

 tn'o eastern Amei'ican species are recogniz- 

 ed, ' B. lanceolatum ' and ' B. caribceum.' The 

 former has an average of (35.6+13.6 + 

 11.8=) 61 myotomes, and the latter an 

 average of (34.8 + 14 + 8.9=) 57.8 myo- 

 tomes, but one individual fi-om the Chesa- 

 peake Bay, referred to ' B. lanceolatmn,' has 

 (36+16+7=:) 59 myotomes, and another 

 -fn. <->»iFlorida, referred to ' B. caribceum,' has (35 + 

 17 + 7=:) 59 myotomes. Inasmuch as no 

 other differential characters have been given, 

 it is evident that Dr. Andrews was mainly 

 influenced by the consideration of associ- 

 ation or geographical distribution rather 

 than morphological characters in the iden- 

 tification of the different specimens. The 

 relations of the forms of our coast, indeed, 

 still remain to be determined, and it is 

 doubtful whether any American forms will 

 prove to be conspecific with the European. 

 Specific characters maj' perhaps be found in 

 numerous details, e. g., the number and pro- 

 portions of the dorsal and ventral or sj'm- 

 podial rays, the development of the cirri 

 and skeletal bases; details of the velar ten- 

 tacles and gillbars, form of the caudal, 

 relative proportions of the various regions, 

 etc. But numerous as have been the me- 

 mou'S on Branehiostoma lanceolatmn, no de- 



tailed study of variations has yet been 

 published. Until this is done much is left 

 undone. The material now in museums,^ 

 however, is generally insufficient for such 

 studies and should be especially prepared 

 therefore. If the labor of students, so often 

 frittered awaj^ in veriijdng oft-repeated 

 observations, could be in part directed to 

 such preparation and observation, a boon 

 to systematic zoology would be realized and 

 certainlj^ no less would be the benefit to the 

 student. We may hope that Mr. AYilley 

 will continue studies so well begun and 

 enlighten us on some of the manj' points 

 still obscure. That we are ignorant as to 

 the questions in point is not his fault. 



The ancestry of the vertebrates is a fas- 

 cinating subject for consideration, and the 

 search for their nearest relatives began 

 early in the century. Before the lancelet 

 was known — at least as a vertebrate — Eti- 

 enne Geofift'oj' Saint-Hilau'e endeavored 

 to homologize constituents of the bodies of 

 insects and vertebrates. (We may here re- 

 mark that Mr. Willej'' has repeatedly refer- 

 red to the French naturalist as Saint Hi- 

 lau-e, bxit Saint Hilaire was onlj^ an ag- 

 nomen, the true cognomen or family name 

 being Geoffrey.) Long after the lancelet 

 had been carefully investigated, and indeed 

 very recently, a naturalist trained in mod- 

 ern methods, but who did not exercise a 

 ' scientific use of the imagination,' actually 

 contended that the vertebrates had arach- 

 noid or rather limuloid ancestors ! A less 

 extravagant view has been that Annelid 

 worms were nearest of kin to the vertebrate 

 ancestors, and this has gained several fol- 

 lowers. But the highlj' specialized character 

 of annelids and still more of arthropods 

 appears to forbid the serious consideration 

 of such conceptions. Much more probable 

 is the view that the nearest relatives of 

 typical vertebrates are the Tuuicates. 

 This is the idea adopted by Mr. Willey, 

 who has accepted a ' group ' called ' Proto- 



