OCR Text |
Show 480 MR. E. T. BROWNE O N [Mar. 17 LEPTOMEDUS^. Fam. THAUMANTID.E. THAUMANTIAS HEMISPELERICA, Eschscholtz. The naturalists who studied marine life at the end of the last century and at the beginning of the present one worked under many 'difficulties which have now passed away, mainly owing to the improvements in lenses and in the advancement of the chemical methods of preservation. The descriptions and figures of the jelly-fishes given by the pioneers of marine zoology usually lack the details necessary at the present day for the identification of the species. The marginal sense-organs or marginal vesicles, which require the use of a microscope to show their presence and structure, have been in most cases omitted, and now recent researches show that they are very important organs for the identification of the species. The early workers on Medusae apparently did not recognize the fact that Medusae, like many other animals, pass through various stages of growth and that the early stages are often unlike the adult forms. This led to the early stages of Medusae being described as distinct species, which together with the vague descriptions given and iuaccurate drawings has led to much confusion. I do not think that any good is to be obtained by retaining inaccurate descriptions of Medusae, and by burdening our literature, already overloaded, with long lists of useless synonyms. Medusa hemisphcerica was first described by Gronovius (1760) from the coast of Belgium. Miiller (1766) described a medusa, as M. hemisphcerica, from the coast of Denmark, and in a later publication (1778) placed Gronovius's medusa as a synonym of it. The descriptions and figures given by these authors are too vague and inaccurate for the identification of the species. Peron and Lesueur (1809) separated the above medusae into two species-M hemisphcerica, Gronovius, and Oceania clanica (Midler). Fleming (1828) changed the generic name to Geryonia, and Eschscholtz (1829) again changed it to Thaumantias and united both species under the name of Thaumantias hemisphcerica. Lesson (1843) has copied from Eschscholtz, without adding any fresh information. Macartney (1810) described two species of medusae taken at H e m e Bay in 1804. The one he called Medusa scintillans, which is described and figured. This is clearly the common protozoon- Noctiluca miliaris. For the other he suggested the name Medusa lucida, but stated that it may be a variety of Medusa hemisphcerica, Gronovius. It is not possible to identify Macartney's medusa from his description. In the same paper Macartney described and figured a large Scyphomedusa under the name of Medusa pellucens. This medusa was taken by Sir Joseph Banks. "On a passage from Madeira to Bio de Janeiro the sea was observed by Sir Joseph |