Vou.2] Esterly—Copepoda of the San Diego Region. 137 
Coloration: Transparent; small amount of red on sides of 
body and faint yellowish tinge to whole, distinct from the glass- 
like clearness of Eucalanus. 
Leneth: Female, 3 mm.; male, 2.7 mm. 
Oceurrence: A female was first seen, San Diego, June 10, 
1904, but two or three occur in most catches when Hucalanus is 
abundant. 
> 
3. Genus Mecynocera I. C. Thompson. 
Leptocalanus Giesbrecht, 1888, p. 334. 
Mecynocera Thompson, I. C., 1888a, p. 150. 
Mecynocera, Giesbrecht, 1892, p. 160; 1898, p. 23. 
Mecynocera Wheeler, 1899, p. 167. 
Furea symmetrical, articulating with anal segment ; mandible 
shorter than maxilla and less than half as long as the fourth pair 
of feet, similar in structure to that of Calanus, but inner ramus 
is nearly as long as second basal and twice as long as outer 
ramus; inner ramus of posterior maxillipeds at least as long as 
first or second basal. First pair of feet with outer ramus of three 
joints, inner of one joint; fifth pair present, with five joints on 
either side. & Unknown. 
2 Head distinct from thorax; rostral threads delicate ; abdo- 
men short, with three segments; genital segment and furea sym- 
metrical. Anterior antennae of unequal length, more than twice 
as long as the body, with 23 joints, bristles few and very long. 
Inner ramus of posterior antennae nearly twice as long as outer 
‘amus. The succeeding appendages, similar to those of Calanus: 
feet short, outer rami with three joints, inner ramus of first pair 
with one joint, of second to fourth with three; fifth pair with 
basals, outer ramus with three joints, inner ramus lacking. 
1. Mecynocera clausi I. C. Thompson. 
Mecynocera clausii Thompson, I. C., 1888a, p. 150, pl. 11, figs. 1-4. 
Leptocalanus filiformis Giesbrecht, 1888, p. 334 
Mecynocera clausii Giesbrecht, 1892, p. 160, pl. 5, fig. 1; pl. 11, 
figs. 43, 45; pl. 35, figs. 21, 22; M. clausi, 1898, p. 23. 
Mecynocera clausii Wheeler, 1899, p. 167, fig. 5. 
The only species of the genus. 
Coloration: Exceedingly transparent, without pigment in my 
specimens. 
