42 NATURAL SCIENCE. July, 



beautiful reports from the pen and pencil of Professor Haeckel, to 

 whom we are once more indebted for the following note : — 



The report on the Deep-Sea Medusae describes and figures (in 

 thirty-two plates) only eighteen new forms, and among these about 

 one-half may not be true inhabitants of the deep sea, but captured 

 accidentally during the hauling in of the net. But of the other half, a 

 part are certainly true deep-sea Medusae, characterised by a quite pecu- 

 liar organisation, viz., among the Craspedotas (or Hydromedusse), the 

 Pertyllidae ; and among the Acraspedae (or Scyphomedusae), the Peri- 

 phyllidae (PI. vii.. Fig. 3), and the Atollidae. As a general intro- 

 duction to this report is given a short sketch of the comparative 

 morphology of the Medusae, based upon investigations of these beautiful 

 Plankton-animals which I had carried on for twenty-five years. 



The report on the Siphonophorse, with its fifty plates, forms a 

 complete though short monograph. Since in my numerous voyages 

 during thirty years I had paid special attention to these most 

 interesting pelagic Hydrozoa, I was prepared to elaborate the 

 materials of the " Challenger," 'of which no naturalist to the Expedi- 

 tion had made a special study. Combining the results of this 

 examination with my own observations made on living animals, I was 

 able to fill up the numerous gaps between the older descriptions, to 

 elucidate many errors, and to give a more complete and consistent 

 idea of the whole organisation than was formerly possible. Among 

 the new Siphonophorae discovered by the " Challenger," special 

 interest attaches to the Auronectidae (with the two families Stepha- 

 lidae and Rhodalidae), which constitute a new order of this class, 

 adapted to deep-sea life in a very remarkable manner. 



Ernst Haeckel. 



echinoderma. 



Crinoidea. — In connection with the " Challenger " Expedition 

 the Stalked Crinoids have a special importance. For it was the 

 discovery of Rhizocnnus, in 1864, by G. O. Sars, and its great interest 

 as resembling extinct forms, which, through the intervention of 

 Dr. W. B. Carpenter and Sir Wyville Thomson, led to the cruise of 

 H.M.S. " Lightning," in 1868. The results of this cruise, notably 

 among Echinoderma, were so remarkable, that it was immediately 

 followed by the expeditions of the "Porcupine," and eventually by 

 the great voyage we now commemorate. It was, moreover, these 

 animals which the original head of the scientific staff wished to take 

 under his particular care, regarding them as " the most remarkable 

 of all the deep-sea groups, both on account of their extreme rarity and 

 of the special interest of their palseontological relations." Formerly 

 regarded as a group " on the verge of extinction," and as pre- 

 eminently abyssal, the Stalked Crinoids have been proved by the 

 dredge of the " Challenger " (nor must we forget that of the 

 U.S. C.S. "Blake "), to be as widely distributed in depth as almost 

 any other group (50 to 3,200 fathoms), while their numbers, in individuals 

 if not in species, show scarcely any decrease from those of Jurassic 

 and Cretaceous seas. Before 1869 only three genera, including five 

 species, of Stalked Crinoids were known. The "Porcupine" added 



