REPORT ON THE SCHIZOPODA. 151 



were, an evenly arched clypeiform shield, that covers about the whole of the body, 

 except a small obtusely conical part jutting out behind, and representing the rudi- 

 mentary tail. It constitutes in the greater part of its extent the immediate wall of the 

 body, being free only in its marginal zone, where it forms merely a slight fold, 

 covering at the sides the bases of the budding limbs back to the oral opening. 



Of the compound eyes, no trace whatever can be detected. Only a small spot of 

 black pigment is observed anteriorly on the median line, and somewhat ventrally, 

 representing the simple larval eye, or ocellus, which, as stated above, also occurs in the 

 adult animal between the insertion of the compound eyes. 



Posterior to the ocellus, and between the points of insertion of the antennse, may 

 be seen inferiorly a rathe,r large carneous prominence, continuous anteriorly ^Aith the 

 front part of the body, whereas, posteriorly, it ends as a free, arcuate edge. This 

 prominence represents the anterior lip, arching partly over the oral aperture. 



The posterior lip, on the other hand, is in this stage quite rudimentary, forming 

 simply two slight transverse prominences (see fig. 3), which do not as yet mark ofi' 

 the oral aperture posteriorly, but lie at a considerable distance behind it, between the 

 budding maxillse. 



Of limbs, only two pairs occur fully develojaed, representing the antennulse and 

 antennae, both of which, but especially the latter, serve as natatory organs. 



The antennulse spring from the ventral face of the liody at a. short distance from its 

 anterior extremity, and point, as a rule, straight forward. They consist of a slender 

 non-articulate stem, about half the length of the body, curving slightly outward at the 

 extremity, which tapers to an obtuse point and bears a few slender set«, one of which 

 is rather elongate. 



The antennae, originating at a short distance posterior to the antennute, are exceed- 

 ingly mobile, and constitute the chief locomotive oi'gans, by the powerful strokes of 

 which the little animal is rapidly propelled through the water. They are of nearly the 

 same length as the antennul?e, but rather dissimilar in structure, consisting of an 

 indistinctly biarticulate and somewhat curved basal part, or stem, from the end of which 

 spring two narrow cylindrical branches of ec[ual size, provided at the tip with several 

 slender and delicately ciliated setse. 



In addition to the parts described above, occur, along the ventral face of the body, 

 four pairs of rounded transverse prominences, arranged sjonmetricaUy on either side, 

 and separated in the middle by a narrow interstice. These prominences, very soft in 

 consistence, and densely cellular in structure, represent the first traces of as many 

 limbs, viz., the mandibles, the two pairs of maxillae, and the maxiUipeds. None of 

 them, however, exhibit as yet the slightest trace of segmentation, or any armature 

 of spines or bristles, forming merely simple buds of the body- wall. 



The anterior pair of these buds, the mandibles, he immediately behind the points of 



