420 Wisconsin Academy of Sciences. Arts, and Letters. 



to the first, is almost triangular, and thinner on the inner mar- 

 gin. The onter part of this segment is thicker, has a short 

 spine in the middle, and ends in a short and ohtuse process. 

 The oblique apical margin of the inner surface has three small 

 incisions. The inner margin of this segment is finely ciliate. 

 The endopodite is one or two-segmented, slender, attenuate to- 

 wards the apex, and reaches to about the middle of the second 

 segment of the exopodite. 



Length of female, 2.3 min. Length of male, 2 mm. 



Pound in the neighborhood of San Francisco. 



The above is the description of DeGuerne and Richard with 

 some slight additions. The species has thus far been found 

 only in the original locality. 



DIAPTOMUS BAKERI Sp. UOV. 



Plate XVI, figs. 4, 5, 6, 9. 



A small species. The first cephalothoracic segment is as 

 long as the three following, the second, third and fourth being 

 about equal in length. The last cephalothoracic segment is 

 armed with two minute spines on each lateral lobe. 



The first segment of the female abdomen equals in length 

 the rest of the abdomen, including the furcal rami. It is broad, 

 dilated in front and laterally, with two small lateral spines 

 about midway of its length. The second segment is very short. 

 The width of the third segment is greater than its length. The 

 furcal rami are about equal in length to the third segment, 

 and are ciliate on the inner mai'gin. 



The antennae are 25-seg'mented and barely reach the end of 

 the furcal rami. The right antenna of the male is much swol- 

 len anterior to the geniculating joint. The antepenultimate 

 segment bears a hook-shaped process which is fully half as 

 long as the penultimate segment. 



The first basal segments of the female fifth feet are armed 

 with rather small spines. The lateral hairs of the second basal 

 segments are short. The exopodite consists of three segments. 

 The second segment is prolonged into a hook which is quite 



