STATE GEOLOGIST. 91 



Diaptomus pallidus, Herrick. 



A more abundant form than the above, though less striking in appearance, is 

 the creature for which this name is suggested. The cephalothorax is more 

 elongate and has but five segments. The antennae are much longer, considerably 

 exceeding the body in some specimens. The joints of the antennas following 

 the geniculating joint are not united or modified, neither is there an appen- 

 dage to the segment immediately preceding. The whole body is slender and 

 graceful, resembling Hemicalanus but the fifth pair of feet is not obsolescent. 

 The secondary antennae were not noticed to have the multiplied intermediate 

 oints in the minor ranius, but such may be the case. 



This animal abounds in the larger lakes, and seems to prefer pure water, while 

 the other is found in more stagnan twater. These creatures are not found infested 

 by bell animalcules and desmids as is the cyclops, probably from their rapid 

 motions and the nature of their haunts. 



D. pallidus may be at once distinguished from longicornis by its lacking the 

 brilliant coloring of the other, it being quite colorless, and by its smaller size. 



D. longicornis is 65-1000 inch in length, while the species in question rarely 



exceeds 40-1000 inch. The eye in this species is also less conspicuous. (See 



plate 11.) 



FAMILY II. Cyclopidae. 



Bibliography —Dana, Rep. Wilkes' Exp. Ex., Vol. XIV. Part 2, p. 1039. 

 Characters. — Eyes small, simple, usually with united pigments. Mandibles 

 with a small or obsolete palpus and few setse. Ova sacs one or 

 two. Primary antennae, often appendaged. Both or neither of 

 the male antennae geniculate. Feet of the first pair more or less 

 prehensile at the end. 

 The prehensile character of the first pair of legs is chosen by Dana as the chief 

 characteristic of the family ; these organs sometimes being perfectly prehensile, 

 with a perfect monodactyle hand, which never occurs in Calanidae. These ani- 

 mals often possess appendages to the first and second segments of the abdomen, 

 as see plate of Canthocamptus, 



The cephalothorax has little variation in structure, having either four or five 

 segments. The anterior antennae are more often much shorter than the body, 

 and if either of them is modified in the male, both of them have a geniculating 

 point. The abdomen is five or six jointed, and may or not be abruptly smaller 

 than the cephalothorax, which fact forms a basis for generic distinction. 



The genus Cyclops possesses two ova sacs, while the ren aining genera, so far 

 as known, have but one. This leads to the division of the family into the two 

 leading sub-families. The third sub-family is founder! by Dana upon some 

 sapphirina-like species of doubtful affinities, described by H. D. S. Goodsir. 



Sub-family 1 Cyclopinw, Dana. 

 Characters. — Ova sacs two. 



Genus 1. Cyclops, Muller. 

 ? Genus 2. Cyclopina, Claus* 



*There are a considerable number of genera of the following sub -families, etc., men- 

 tioned in Glaus' " Zoologie", wliich are, for the most part, not descJribed. Since I 

 have not been able to consult the works in which they are defined, and since he seems 

 not to recognize many of those described by Dana, and to disregard his classification, 

 the deciphering of their relation and situation will not be attempted here. 



