. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. ECHINOIDKA. 11. ^n (Panainic Deep-Sea Ecli. p. 163) to the .i^euns IHlematechinus established there for Cystcch. Ratlibunl. — A few remarks on the forms mentioned aljove mav be j^iven here. Cystechmus clypcatits. In the description of this .species ( Chall. -Ech. p. 149) Professor Ag-assiz remarks that in the specimens from tlie greater depths (ca. 19a:) fathoms) the test is much tliinner than in tlie fragments which are found near the ickxj fathom hne . This mav perhaps be true for other
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. ECHINOIDKA. 11. ^n (Panainic Deep-Sea Ecli. p. 163) to the .i^euns IHlematechinus established there for Cystcch. Ratlibunl. — A few remarks on the forms mentioned aljove mav be j^iven here. Cystechmus clypcatits. In the description of this .species ( Chall. -Ech. p. 149) Professor Ag-assiz remarks that in the specimens from tlie greater depths (ca. 19a:) fathoms) the test is much tliinner than in tlie fragments which are found near the ickxj fathom hne . This mav perhaps be true for other species (Agassiz refers to Pourtalcsia, Cystechinus and Urrchinus), though I do not see any such difference among the specimens of U. naresianus from the Ingolf ; but as for C. clypeatus the difference in the thickness of the test is in any case not alone due to the different depth at which the specimens lived, but also to their being different species, as I can state after having examined the fragments preserved in the British iMuseum; the pedicellarise differ .so considerabK- that it seems quite impossible that they can belong to the same .species. Also the structure of their apical svs- tems will probably be found to differ considerablv. In the description it is said: The al)actinal system closely resembles that of Cysfechii/iix \]\vvillii; the genital plates are, however, proportionalh' larger, the left anterior and the right posterior far exceeding the others in size, and extending entirely across the abactinal area, the whole central part of which is formed by the junction of the genital plates . But the figure, PI. XXXV. b. 10, is, as will be seen, not in accordance with that description; the left anterior and right posterior genital plates do not exceed the others in size or extend entirely across the abactinal area, and the whole central part is not formed by the junction of the genital plates, the large ocular plates of the anterior paired ambulacra separating wideh
Size: 1356px × 1843px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
