1883. ] Zoology. 885 
effected by forcing the water to and fro. In this fact we find, 
probably, the explanation of the very early appearance of buds 
upon the axial polyp.” 
| cts, of development, as far as they go, indicate the deri- 
vation of Renilla from a form related to the Bathyptileæ, which 
probably possessed a horny axis. Bilateral symmetry is strongly 
exhibited both in the individual polyps and in the entire colony. 
The author concludes that the bilateral environment determines 
the bilateral structure. 
Finally discussing the polymorphism of Renilla, the author 
attempts to show that the zodids are probably not degenerate 
polyps, but buds in a state of arrested development, whose direct 
ancestors never possessed a more highly organized structure than 
at present. 
A new Parasitic Copepop CrusTacean.—During the summer 
of 1880 and 1881 I received alcoholic specimens of a Caligus or 
fish-louse, gathered from the skin of the “salmon”! inhabiting 
Puget sound, Washington Territory. 
form is convex, ovoid, color on dorsal surface dark rufous, on 
A pe s 
f Cali- 
This 
second abdominal segment measures 2™™ in length exclusive of the appendages, and 
three-fifths of a millimeter at its widest diameter. After treating it with acetic acid it is 
seen to consist of four distinct segments, This segment is cylindrical in form, slightly 
tapering toward its tip. The mandibles of the buccal mass appear to two-jointed, 
the basal joint probably movable, the second joint connate. The first maxilliped is 
provided with a knob-like lateral process on the penultimate joint. This process is 
ansversely ruled with parallel rugose lines, rendering it fit for trituration, The 
large hooked spine, the outer branch of the first maxilliped, is present and is of the 
same form as in Caligus americanus. secon i i 
has the shape of a short, thick, hexapodous mandible, is deeply cleft at its middle. 
The first pair of maxillipeds is two-jointed ; instead o ensiform extension it is 
furnished with a sharp tooth at the inner side near the middle of the second joint. 
This second joint terminates with a longer and a shorter blade-like flat bristle edged 
i ow illi as a very 
joint, the claw. The second pair of natatory legs its second joint continuous 
h superior or outer branch. interior or inner branch is not connate with 
second, but with the first joint of the superior branch. The inferior branch has 
uperi as four long and three shorter pinnulæ and 
several larger spines.. Not too much stress should be put on such inferior charac- 
ters, as I have met with two i mericanus having also eight 
femal 
pinnulæ on the inferior branch of the same leg. 
1 Probably the “ blue-back salmon.” See AMER. NATURALIST,1881, p. 177, “ Ob- 
servations on the salmon of the Pacific,” by D. S. Jordan and Ch. H. Gilbert. 
Amer. Four. Sci. and Arts, 18 
