400 PROCEEDINGS OF THE ACADEMY OF [1897. 



Length 15 mm., breadth 4.8 mm. Types (No. 20,501, U. S. N. 

 M.). 



Synidotea muricata (Harford). Fig. in. Hotcea muricata Harford. Proc. Cal. 

 Acad. Sei., VII, Pt. I, p. 117, (1876), 1877. 



Six specimens, taken by the 'Cor- 

 win ' off Icy Cape differ from all 

 other species of the genus yet de- 

 scribed by the spiny nature of the 

 dorsal surface, head and pleon in- 

 cluded. The locality is lat. 70° 

 15' 00" N., long. 162° 55' 00" W., 

 in 25 fathoms. 



The head is deeply excavated in 

 front, the margin running inward 

 from the lateral prolongations to a 

 median notch. The flagella of the 

 antennjB have from 10 to 12 seg- 

 ments. A small spine overhangs 

 the median notch, a second spine 

 is situated a little behind the first, 

 a third is in line on the posterior 

 lobe; two other spines, one on each 

 side of the first two, form, in con- 

 nection with them, the figure of a diamond; the spines of the median 

 line are at the obtuse angles. A little behind the margin and in 

 front of the eye is a short spine with a compressed base. Spines 

 with compressed bases are not peculiar to the front, but begin on the 

 postcephalic lobe and extend to the end of the thorax situated on 

 transverse ridges and forming the median line of spines. The 

 spines on the abdomen are not compressed. On either side of the 

 median line is a lateral line of spines ; below these spines on each 

 segment is a group of five spines arranged in two transverse rows, 

 three in the anterior and two in the posterior rows. The abdomen 

 has two transverse ridges, the basal ridge has three spines and the 

 next ridge five. On each side is a group of from five to nine very 

 short spines, the number varying according to the size of the speci- 

 men. The abdomen is broad at the base, constricted at about the 

 middle and runs out to an acute terminus. The specimens have 

 been in poor alcohol too long to make color notes of any value. 

 Length of a large specimen 21 mm., breadth 7 mm. 



Fig. 10. Synidotea muricata 

 Harford, x 2i. 



