230 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



But only he who is fortunate enough to have access to 

 the type specimens can attempt to revise the specific 

 nomenclature, and, even then, his success may be doubtful, 

 as so many of the type specimens are preserved in the 

 dried condition. 



This paper consists of two parts, the first containing 

 the revision of the generic nomenclature. It is meant to 

 be used with the plates in the third and fourth volumes 

 of the Monograph. The left of the two columns gives 

 Bowerbank's nomenclature, the right the revised nomen- 

 clature, beginning with the first plate in the third volume 

 and ending with the last plate in the fourth volume. The 

 numbers of the plates in the third volume are simply 

 indicated by Koman numbers, but those in the fourth 

 volume by Eoman numbers preceded by "4." 



The second part of the paper contains the classified 

 list of all species described by Bowerbank, with their 

 revised generic names only. References to the plates in 

 the two volumes are given in each case, so that, by 

 referring back to the first part of the present paper, the 

 old name is easily ascertained. In many cases references 

 are added to other works in which Bowerbank's species 

 have been redescribed, or which otherwise bear upon 

 the subject. 



I have thought it useful to give the generic definitions 

 of all Monaxonida, because they have been compiled from 

 various authors. I have to acknowledge my indebtedness 

 to Ridley and Dendy's "Challenger" Report {14) and 

 perhaps still more to Topsent's recent writings {18, 19, 

 20). Many of the generic definitions are literally, or 

 almost so, copied from those sources. Thus also the 

 classification of Halichondrina is taken from Topsent's 

 latest paper {20). Valuable aid was also obtained from 

 von Lendenfeld {11, IS) and Vosmaer's works {22). 



