Annual Report of the Commissioners of Inland Fisheries Made to the General Assembly (Volume 10th 1881)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ...on the under side of the abdomen have become larger and stronger and fringed with a heavy border of setae. They become highly functional in this stage. 6. The exopodites and endopodites arising from the last abdominal segment and forming with the telson the tail-fan have developed in size and now are equal in length to the telson itself. They too are fringed with a heavy border of long setae. 7. The average length of the fourth stage lobster is about 13 mm.; it is now almost the epitome of the adult lobster. In the succeeding stages of the young lobster many of the changes which take place may be noted, not so much with reference to any definite stage as with regards to the continued development as a whole. Of these we may note the following: 1. The eyes become less and less prominent as the stages advance. 2. A broadening and thickening in the body occurs. a. In the male this takes place in the cephalo-thorax. b. In the female, the broadening is in the abdomen. 3. There is a thickening and strengthening of all the body appendages with a gradual variance in the appearance of the right and left chelae. Fifth Stage. The fifth stage lobster is too immature to at once manifest many of these changes; the chief characteristic of this stage being the prominence of the basal joints of the first antennae, as in contrast to this position under the rostrum border in the fourth stage. (Plate XI.) The average length of the fifth stage lobster is 15-16 mm. Sixth Stage. The point of distinction of the sixth stage is the beginning of a differentiation in the shape of the chelae, the right manifesting a tendency to develop into the nipping claw, the left into the crusher. This change sometimes is not evident until the seventh stage. The external...