4 University of California Publications in Zoolofjjj [Vol. 13 



(1893, pp. 5 and 6) has j^'iveii a contrast iii<i' tMl)iilar sunnnary of the 

 characters of the Euphausiacea and Mysidacea. 



Within the Enphansiidae there are three subfamilies according 

 to Holt and Tattersall (1905). In the collections from this region 

 two of these are represented, the Euphausinae and the Nematoscelinae, 

 the former by the genera Evphausia Dana and Nyctiphanes Sars, 

 and the latter by TJi.ysanoessa Brandt, Nematoscelis Sars and Stylo- 

 cheiron Sars. The descriptions of genera and species given here are 

 necessarily repetitions of those already published elsewhere because 

 no forms have been found that are certainly new. It has seemed 

 desirable, accordingly, to limit the text to accounts of the most easily 

 recognized and most characteristic particulars, and to show in the 

 figures those structural points that in connection with the text wull 

 render it possible to verify identifications. No attempt has been made 

 to consider or refer to the literature previous to the Challenger Re- 

 port on the Schizopoda (Sars, 1885), nor is the list of papers since 

 then nearly complete. 



The discussion of the distribution and movements of the more 

 abundant Schizopoda as shown by the data obtained by the Institution 

 is reserved for another paper, in which a full list of the hauls con- 

 taining Schizopods will be given with the number of each species in 

 each haul. 



ORDER EUPHAUSIACEA 



The keys given here are largely adapted from Zimmer (1909) 

 and from Hansen (1911). I have included the genera Siriella and 

 Neomysis in the key for the Mysidacea, since they occur on the coast. 

 Holmes (1900), Hansen (1913), although I did not find represent- 

 atives of them in the collections I examined. Account has also been 

 taken of Thysanoessa raschii M. Sars in the key for the Euphausiacea, 

 following the statements of Hansen (1911, p. 8). This species has 

 been recorded from the Pacific Coast by Hansen (1913, p. 174), and 

 does not have the elongated inner ramus in the second thoracic limb. 

 If the inclusion of T. raschii stands, it will necessitate modifying the 

 descriptions of the sub-families Euphausinae (Holt and Tattersall) 

 and Nematoscelinae (Holt and Tattersall). 



