ON THE ASTEBOIDEA OF H.M.S. ' CHALLENGER ' EXPEDITION. 189 



The Asteroideca of H.M.S. ' Challenger ' Expeditiou.— Part T, 

 By W. Peect Sladen, F.L.S., F.G.S. 



[Eead Januaij 19, 1882.] 



[Published by permission of the Lords Commissioners of tlio Treasury.] 



Part I. PTEEASTERID^. 



The Asteroidea collected during the expedition of H.M.S. ' Chal- 

 lenger ' were kindly intrusted to my care by Sir C. Wyville Thom- 

 son in the early part of the past year (1881), to report upon and 

 describe. As might naturally be expected in a group of animals 

 of such universal occurrence, the amount of material is very 

 great, and furnishes additions of the highest importance to our 

 knowledge of the geographical and bathymetrical distribution of 

 species, of variations of form within areas of occurrence, and of 

 growth-stages ; whilst the number of species new to science is 

 also very considerable. These circumstances, together with the 

 fact that comparatively little has hitherto been known respecting 

 the Asterid fauna of abyssal depths, are sufficient to indicate 

 the interesting and important character of the collection under 

 notice. 



It is my intention to lay before this Society an account of the 

 species obtained, with descriptions where necessary, and to pre- 

 sent the same by instalments during the course of the prepara- 

 tion of the detailed Eeport, which will ultimately form a part of 

 the Official Report of the Voyage now in process of publication. 

 In the issue of the proposed preliminary lists I shall not feel 

 called upon to adhere rigidly to the sequence in which families or 

 genera are classified by systematists. The parts will more pro- 

 bably be issued as soon as my examination of special groups is 

 completed ; and this, for obvious reasons, will be determined in 

 a great measure by conveniences of study and comparison. By 

 this means I hope to be able to lay more speedily before specialists 

 an outline of the results of the Expedition as far as the Asteroidea 

 are concerned, and thus render them available for general consul- 

 tation and reference. All questions of anatomy, development, 

 variations, and general deductions will be reserved for the lloport 

 above mentioned. 



