88 PROCEEDINGS OF THE NATIOXAL MUSEUM. vol.53. 



Internally there is a large tripartite eye a little in front of the 

 center of the cephalothorax. The testes are paired and at the extreme 

 posterior margin of the cephalothorax ; the sperm ducts open out of 

 their posterior ends and run back to the genital segment where each 

 is enlarged into a pair of receptacles within which are formed and 

 stored the spermatophores. 



Total length, 1.75 mm. Diameter of cephalothorax, 0.45 mm. 



Nauplius. — General outline diamond-shaped, considerably flattened 

 dorso-ventrally, a trifle longer than wide, all thecorners well rounded. 

 Three irregular patches of pigment on the dorsal surface, one at 

 each of the lateral angles and the third at the posterior angle. The 

 anterior angle is filled by the large compound eye, whose pigment is 

 the same color as that of the dorsal patches, a yellowish purple. Be- 

 hind the eye may be seen the first traces of the nerve ganglion, not 

 as yet clearly developed. And behind the ganglion, occupying the 

 bulk of the center of the body, is a single large oil globule similar 

 to that noted in Lernaeenicus longiventris (p. 68). First antennae 

 armed with a bunch of short spines on the dorsal surface near the 

 distal end and the usual tw^o long terminal plumose setae. Second 

 antennae and mandibles of the typical pattern, biramose, the exopod 

 four-jointed, each joint bearing a plumose seta, the endopod with a 

 single joint tipped with tw^o setae. Balancers slender and curved, 

 turned at right angles to the body axis so that the two are in the same 

 straight line. 



Total length, 0.45 mm. Greatest width, 0.40 mm. 



Mefanauplius. — General outline an elongated oval, the pointed end 

 posterior, the margin evenly rounded. The posterior pigment spot 

 has increased in size while the lateral ones have fused across the mid- 

 line. The eye is relatively smaller ajid not as close to the anterior 

 margin. The appendages remain approximately as before except 

 that the endopods of the second antennae and mandibles are now dis- 

 tinctly jointed, and the terminal joint of each is armed on the inner 

 margin with a stout spine. At the posterior end of the body inside 

 of the skin may be seen the beginnings of two free thorax segments, a 

 fused fifth and genital segment, and a one-jointed abdomen with anal 

 laminae. The balancers turn forward as before, but are now jointed 

 close to their base, while the terminal portion is flattened dorso-ven- 

 trally and Wuntly rounded at the tip. Between these from the ])os- 

 terior end of the body projects a short conical process, with a pair 

 of blunt rounded spines on either side at its base. 



This is the posterior body of the metanauplius, while that which is 

 seen inside of the skin is to become the posterior body of the first 

 copepodid larva after the next molt. 



Total length, 0.55 mm. Greatest width, 0.25 mm. 



