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embryo Lernaea, from which also tubular processes extend 

 in two (Achtheres) or three (Lernceocera) pairs, including 

 setae which project from their extremities. 



In the Lernaocera the anterior pair is directed forward 

 like antennae, but they are unjointed; and the head is 

 further indicated by a coloured eye-speck. Another layer 

 of germ-cells has perished, as such, in order to form the 

 parietes of a straight and simple intestine, with a mouth 

 and anus. Thus the annelidous type is first manifested. 



But a large proportion of the minute germ-cells remain 

 in the wide abdominal interspace, amassed around the 

 alimentary tube, and aggregated in groups at the base of 

 the tubular arid setigerous feet. With respect to the latter 

 we might say that the same provision is made for the re- 

 production of the limbs as is retained throughout life in 

 regard to those of the Lobster. In the larval Lernaea, how- 

 ever, those reserve-cells commence the formation of new 

 limbs irrespective of any injury to the old ones. The 

 whole peripheral stratum of the retained germ-mass in con- 

 tact with the primary integument is transformed into a new 

 integument. These germ-cells have increased and propa- 

 gated at the expense of the aliment assimilated by the 

 alimentary canal. The formation of the new integument 

 and of the new feet proceeds connectedly and contempo- 

 raneously : but the new parts are not moulded upon the 

 inner surface of the old ones. The plastic force has 

 changed its course of operation. A hinder segment of the 

 body is added to the front one which answers to the whole 

 of the body of the first larva. If antennae did not before 

 exist, a jointed pair is now developed. Instead of two 

 pairs of tubular setigerous limbs, three pairs of uncinated 

 prehensile limbs are developed from the anterior or cepha- 

 lothoracic segment, and as many pairs of articulated seti- 

 gerous limbs from the abdominal segment. New muscles, 

 new nerves, and new vessels are formed for the support 

 and exercise of these various instruments. The outer 



