230 CALIFORNIA ACADEMY OF SCIENCES. 



exopod reaching the tip of the first joint of the endopod; third joint of 

 the endopod about equalling the two following; last joint about one-fourth 

 the length of the preceding one. The four succeeding pairs of pereopods 

 are similar to the first but decrease successively in length posteriorly. 

 The penultimate pair of pereopods is very small; the endopod is two- 

 jointed, the tip of the first joint nearly reaching the tip of the exopod. 

 The last pair of pereopods is probably represented by a minute styliform 

 appendage on the last tuft of branchiae. Abdomen slender, the lateral 

 angles acute, the first five segments cariuated above, the carinse on the 

 fourth and fifth segments ending posteriorly in a long spine; sixth seg- 

 ment rounded above but ending posteriorly in a small spine which is 

 curved downwards. Telson long, deeply channelled above, the anterior 

 fourth with the sides nearly parallel, the posterior portion tapering to the 

 acute tip; subapical spines extending beyond the tip; a pair of uiarginal 

 spines near the middle of the dorsal surface and another pair above the 

 bases of the subapical spines. Uropods subequal to the telson, the inner 

 ramus narrowly lanceolate; outer ramus much broader and slightly longer 

 than the inner, the outer angle subacute. 

 Length, 30 mm. 



Taken near Fort Bragg, Calif., June, 1894. 



This species may be distinguished from T. longipes 

 Brandt by its more slender rostrum, differently shaped 

 antennal scale, by having the third basal joint of the 

 antennules shorter, instead of longer than the second, 

 and in having the first pair of pereopods considerably 

 shorter. The cornese are nearly round and not divided 

 by a constriction into an upper and a lower portion as 

 in T. gregaria and macroura described by Sars. 



Collection University of California. 



Thysanoessa gregaria Sars. 



Thysanoessa gregaria Sars, Forhandl. Vidensks. Selsk., Christiania, No. 

 7, 1883; Challenger Keports, Vol. XIII, 1885, p. 120, PI. XXI, figs. 

 8-17; PI. XXII, figs. 1-30. 



Kostrum large, triangular, acute; antero-lateral angle of the carapace 

 produced into a sharp, triangular process; lower margin of the carapace 

 with a small tooth behind the middle. Eyes very large, subglobose, the 

 upper part of the large cornea constricted; an incision between the smaller 



