708 PROF. A. BENDY AND MR. R. W. H. ROW ON 



specimens, to be erroneous. Further, we have felt that we could 

 not, merely on the basis of these published descriptions, vinder- 

 take the responsibility of determining whether or not a species 

 described as new by its author should more properly have been 

 allocated to a previously known species. Thus we have proceeded 

 on the principle that all species described as new must be con- 

 sidered to be distinct, unless they have been proved to belong to 

 a previously known species by the subsequent reinvestigation of 

 type specimens or otherwise. We have only given such synonyms 

 and references as seem absolutely necessary, but where one species 

 has been merged in another by any authority, and this result 

 accepted by us, we give the synonym and the appropriate 

 authority under the species in which it is now placed. 



It is thus highly probable that, of the 436 species which Ave 

 enumerate, a considerable proportion will ultimately prove to be 

 identical with one another. This question, however, can only be 

 decided by a very thorough study of the specific chai"acters and 

 range of variation in each case, probably necessitating in many 

 cases a reinvestigation and comparison of the original types. 

 Professor Minchin, in his paper on " The Characters and 

 Synonymy of the British Species of Sponges of the genus Leuco- 

 solenia" [1905], has set a good example of the manner in which 

 this critical revision of the group ought to be carried out. 



We have, as a general rule, taken no notice of varieties as 

 distinct from species, but certain of Haeckel's so-called " Specific 

 Varieties," to which he has already given distinctive names, 

 appear to us, after careful consideration of his descriptions, to 

 deserve to rank as separate species. 



In the preparation of this paper we have throughout borne in 

 mind the requirements of the systematist, and it is hoped that 

 its publication will greatly assist the determination and arrange- 

 ment of species in the future. We have had to set aside a great 

 number of published generic names as synonyms, but it is hoped 

 that the appended list will enable the student to trace them in 

 the present system. 



We have indicated in the list of species under each genus that 

 species which we recognise as the type, our method of procedure 

 being to take, in the case of old genera, that species, of those 

 which we assign to the genus, to which the name of the genus 

 was first applied, while in the case of new genera we have 

 chosen as our type the species which seems to exemplify best 

 the special characters on which we have founded the genus. 



As the publication committee of the Zoological Society has 

 decided against the use of brackets around the names of authors 

 of species in all cases, it must be understood that the authors 

 cited are responsible for the specific but not necessarily for the 

 generic names employed by us. 



