Guide to the Crustacea, Arachnida, Onychophora and Myriopoda exhibited in the Department of Zoology, British Museum (Natural History) .. . hough the firm outer covering is really continuous over thewhole of the surface of the body and limbs, it becomes thinned awayin places to form joints permitting movement between the variouspai-ts. Thus, the body and limbs are divided into segments * * The word joint, often applied to these divisions of the hody andlimbs, ought properly to be restricted to the hinge or connection between twosegments. The Lobster as a type of Crustacea. 13 which, in the case
Guide to the Crustacea, Arachnida, Onychophora and Myriopoda exhibited in the Department of Zoology, British Museum (Natural History) .. . hough the firm outer covering is really continuous over thewhole of the surface of the body and limbs, it becomes thinned awayin places to form joints permitting movement between the variouspai-ts. Thus, the body and limbs are divided into segments * * The word joint, often applied to these divisions of the hody andlimbs, ought properly to be restricted to the hinge or connection between twosegments. The Lobster as a type of Crustacea. 13 which, in the case of the body, are termed body-segments or somites. A study of the various modifications of structure presented by Wall-casesNos. 1-3. Crustacea and other Arthropoda has led to the conclusion that ^^^^^ they are to be regarded as built up of a series of somites or body-segments, which may be distinct or soldered together, and each ofwhich bears typically a single pair of limbs or appendages. Thus, in the Lobster (Fig. 1), the hinder half of the body (orabdomen) is plainly made up of six somites (besides a tail-piece or Cefihalothorax. The Common Lobster ( <j(i))imurns). Female, from the side.[Wall-case No. telsoii), each of which carries on the under side a pair of swimmerets. The front half of the body is not so divided, butis covered by a large shield or carapace which projects betweenthe eyes as a toothed beak or rostrum. Since, however, thispart of the body also bears a number of appendages constructedon the same plan as the swimmerets of the abdomen, it is con-cluded that here also we have to do with a series of somites,although they are so completely fused together as to be indistin-guishable except by their appendages. That this conclusion iscorrect is proved by comparison with some of the lower Crustacea,for instance, Anaspides (see Table-case No. 5), in which there is no 14 Guide to Crustacea. Wall-casesNos. 1-3. carapace, and the fore part of the body h
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectcrustacea, bookyear19
