24 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 60 



a sand shark, Carcharias Ufforalis, at Woods Hole was taken by Dr. 

 Edwin Linton and has been given Cat. No. 53570, U.S.N.M. Two 

 females and a male from the mouth of a mackerel shark, I sums oxy- 

 rhynchus^ were taken June 17, 1888, by Vinal Edwards at Woods 

 Hole and have been given Cat. No. 53571, U.S.N.M. 



Specific characters of female. — In addition to what has just been ' 

 given under the generic characters we may note the following : The 

 carapace covering the cephalothorax is yellowish broAvn, deeper in 

 color through the center and paling towards the margins. The 

 antennal area is separated from the rest of the head by well-defined 

 marginal invaginations and by a somewhat indistinct dorsal groove. 

 In the larger and more mature females there is usually in invagination 

 at the center of the posterior margin of the carapace, sometimes ex- 

 tending quite a distance as a triangular slit. In younger females 

 and sometimes in older ones the margin is entire. The carapace 

 projects backward over the free thorax and overlaps the genital 

 segment. On the dorsal surface of the fourth segment is a pair of 

 large elytra which entirely cover the posterior part of the body and 

 overlap along the median line. These are white in color like the 

 membraneous legs and are similarly covered with minute trans- 

 parent dots or depressions. 



The genital segment is oblong with nearly parallel margins, the 

 proportion of the length to the width being as 4 to 3. The egg strings 

 are attached to its posterior margin, considerably below the dorsal 

 surface, side by side on the median line. 



The abdomen is attached to the ventral surface of the genital seg- 

 ment below and in front of the bases of the egg strings. It is made 

 up of a single small joint. The anal laminae are thick and fleshy, 

 much longer than the abdomen itself, and they taper to a blunt point. 

 They are entirely destitute of setae and spines. 



The first antennae are rather long, seven- jointed, thickest through 

 the tip of the third joint, and thence tapering gradually. Below and 

 behind the basal joint of each antenna, and filling the marginal notch 

 in the carapace, is a thick triangular process or palp. Wlien the an- 

 tenna is folded back against the carapace this process is nearly con- 

 cealed, but it stands out prominently if the antenna be turned forward 

 at right angles to the body axis. The joints of these antennae are only 

 sparingly supplied with setae. The second antennae are transformed 

 into strong attachment organs. They are three- jointed, the basal 

 joint much swollen, the second joint narrowed distally and armed 

 on the ventral surface with a stout peg so placed as to interlock with 

 the tip of the terminal claw. The latter is short and is bent into a half 

 circle. 



The upper and under lips are fused and produced into a long, stout 

 and bluntly rounded mouth tube. At its base on either side are 



