I06 PATTEN AND REDENBAUGH. [Vol. XVI. 



and the anterior edge of the carapace (see Patten, Qnar. Journ. 

 Micr. Set., 1893). The seven pairs of appendages surround 

 the mouth (PI. VIII, Fig. 3, wz.), which lies nearly in the center 

 of the cephalothorax. The nephridial openings (PI. VII, Fig. 2, 

 n.o.) may be seen just back of the fifth pair of legs. 



The abdomen (Pis. VI and VIII, Figs, i and 3, vies.) is 

 attached to the cephalothorax by a transverse hinged joint on 

 the haemal side of the animal, and is capable of movement in a 

 haemo-neural direction only. It bears on its lateral edges six 

 pairs of spines (PI. VI, Fig.i, a-sP-'^f), the first pair belonging 

 to the first branchial metamere, and the last pair to the first 

 post-branchial metamere. 



On the neural surface of the abdomen are six pairs of lamellar 

 appendages (PI. VIII, Fig. 3, ap.^-'^) ; the genital openings 

 are on the posterior side of the first pair of abdominal append- 

 ages, and the anus (Pis. VI and VIII, Figs, i and 3, a.) is at the 

 base of the caudal spine. 



The caudal spine (Pis. VI, VIII, and IX, Figs, i, 3-5, tel.), or 

 telson, is a long, sword-shaped, terminal segment capable of 

 movement upon the abdomen in any direction. 



E7itapopJiyses. — Seven pairs of entapophyses, or chitinous 

 infoldings of the haemal side of the carapace (Pis. VI, VIII, 

 and IX, Figs, i, 4-6, entay~"f), serve for the attachment of 

 muscles. These infoldings may be seen from the exterior; one 

 pair {enta^'^) on the cephalothorax, just anterior to the hinge, 

 and the other six pairs {entaP~'^) upon the abdomen. The 

 first pair {enta.T^), which are much larger than the others, 

 are probably formed by the fusion of the two pairs belonging 

 to the chilarial and opercular metameres ; the next five pairs 

 (cntaP''^) upon the abdomen belong to the five gill metameres ; 

 the last pair (cnta.''>) belong to the first post-branchial metamere. 



Tendinous Stigmata. — Six pairs of chitinous infoldings of 

 the neural surface of the abdomen, close behind the bases of 

 the six pairs of abdominal appendages, serve for the attachment 

 of the branchio-thoracic muscles. They have received the name 

 of tendinous stigmata (Pis. VI and IX, Figs, i and 6, t.s.^''^). 



The Appendages . — In describing the appendages it seemed 

 desirable to consider them all as turned outward so as to lie at 



