2 I. IJIMA : IIEXACTINELLIDA. I. 



If future circumstances should make it appear desirable, I 

 may undertake in a separate memoir to give a synthetical 

 representation of accumulated facts relating to, and the systematic 

 of, the Hexactinellida in general, accompanied with as complete 

 a list of relevant literature as I can bring together. 



The appearance in 1887 of F. E. Schulze's ' Challenger ' 

 Keport on the Hexactinellida — it need scarcely be said — has 

 marked a new era in the history of our knowledge of this inteiest- 

 ing group of the Spongidn. In spite of the rich material described, 

 the author at the close of that great work (p. 452) has given 

 grounds to believe that only a relatively small percentage of the 

 really existing Hexactinellid species was then known. Since 

 that time, indeed, a considerable number of important additions 

 to our knowledge of the group has from time to time been 

 made, chiefly by the indefatigable zeal of that same distinguished 

 investigator. The fact that this progress has been possible 

 seems to give us still the promise that our present knowledge on 

 the subject will yet be greatly extended and improved tlirough 

 further explorations and researches. 



At the time that I took up the study of Hexactinellids, 

 there were known in all from the Japanese seas 17 species (G 

 Lyssacina and 11 Dictyonina). These were as follows: 



1. Eupleclella otven! Marsh. 



2. Acanthascus cactus F. E. Sch. 



3. RhabdocalyiJtus mollis F. E. Sch. 



4. Q'ateromorpha meyeri Gray. 



5. Hyalonema siebohli ,, 



6. „ affine Marsh. { = H. apcrium F. E. Sch.) 



7. Farrea occa Carter. 



8. ,, vosmceri F. E. Sch. 



