clxvi GENERAL SUMMARY OF SCIENTIFIC AND 



VERTEBRATE ZOOLOGY. 



By Db. THEODOKE GILL. 



Vertebrate Zoology has received the average amount of attention 

 devoted to it for the last few years. Valuable contributions have 

 been made to the morphology and anatomy of the branch, and its 

 several classes ; numerous species have also been added ; and several 

 very interesting new types have been made known. Unquestionably 

 the most noteworthy of these are several forms collected in the Aus- 

 tralian and Ethiopian realms : these are (1) a species of the genus 

 TacJiyglossus or Echidna, which has been supposed hitherto to have 

 been confined to Australia and Van Diemen's Land ; (2) a remarkable 

 new generic type, representing a previously unknown family, found 

 in Africa ; and (3) a second genus of the hitherto monotypic class 

 of Leptocardians. The significance of these discoveries will be made 

 manifest in our subsequent remarks. 



Almost if not quite the jnost interesting of animals has been the 

 Braiichiostoma lanceolatum (often called Amphioxus lanceolatus), until 

 lately the type of the only known genus of not only a class, but 

 even, in the opinion of many, a primary group or " superclass" of the 

 branch of vertebrates. The genus owes its interest and importance 

 to the fact that it is, to most intents and purposes, an " invertebrate 

 vertebrate ;" and that it gives, in its organization, the chief if not the 

 only clew to the derivation of the vertebrate phylum in its diflferen- 

 tiation from the mass of the animal kingdom. Through the careful 

 study of that interesting form, naturalists had arrived at the conclu- 

 sion that the vertebrates were derived in all probability from the mol- 

 luscoid Tunicates. Unusual interest is, therefore, attached to the dis- 

 covery of an apparently well-defined second genus of the family. Its 

 type was discovered in Moreton Bay, North Australia, by the captain 

 of the German Imperial vessel Gazelle. The new genus differs from 

 BrancTiiostoma in the development of a high dorsal fin ; in the 

 want of a distinct caudal as well as anal fin ; and in the symmetrical 

 median (not lateral) position of the anal aperture. It appears also 

 to present some difierences of detail in the structure of the mouth 

 and oral tentacles ; but these characters require yet to be elucidated. 

 The type of the genus is much smaller than the species of the genus 

 BrancMostoma. Ten specimens obtained vary from thirteen to twen- 

 ty-three millimeters in length. The newly discovered type has been 

 described by Dr. Peters, of Berlin, under the name of BpigonicMM/s 

 cultellus. The generic name was apparently given in allusion to the 



