Items related to Studies on Apus, Limulus and Scorpio
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881. Excerpt: ... as to the presence or absence of a motile flagelliform tail. In Crustacea generally they are immobile and of very various shapes; but in Cirrhipedia, and possibly some others, they are filamentous, with a motile tail. In chilopod Myriapods they have a vibratile tail. In Chilognaths they are motionless. In hexapod Insects they have a vibratile tail. In some Arachnida (e. g. Spiders) they are devoid of such a process. We owe to Kolliker the observation that in the Scorpio europaus the spermatozoa are filamentous in form, with a vibratile tail. Accordingly, it is compatible with Arachnidan affinities for the spermatozoa to be either motile or immobile; at the same time, as an element in the cumulative evidence of affinity between the King Crab and Scorpion, which it has been my object in this essay to bring together, the presence of vibratile spermatozoa in Limulus is a fact of value. The spermatozoa of Limulus are, as I observed four years ago (4), provided with a long vibratile tail; they agree, therefore, with those of the Scorpion. C. The Eurypterina As A Connecting Link Between Limulus And Scorpio. The intimate affinity of the extinct Eurypterina with Limulus is no longer doubted. The researches of Hall, Huxley, and Woodward, have thoroughly established the fact that Pterygotus, Eurypterus, Slimonia, and Stylonurus, are to be regarded as Limuli, in which one pair of leg-like organs (probably the most anterior) has been suppressed, and in which the telsonic region, instead of exhibiting but an imperfect development of segments posterior to the twelfth, and that only in the embryo, gives rise to a series of segments forming a large tail-like region of the body. The result of this development of segments between the anus and the last appendage-bearing segm...
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