ARCHICOPEPODA. I I I 



The eyes of copepods are of interest, in that they suggest the paired ocelli of the Har- 

 pedid^e and Trinucleidae. In the Copepoda there are, in the simplest and typical form of 

 these organs, three ocelli, each supplied with its own nerve from the brain. Two of these 

 are dorsal and look upward, while the third is ventral. In some forms the dorsal ocelli 

 are doubled, so that five in all are present (cf. some species of Harpes with three ocelli on 

 each mound). In some, the cuticle over the dorsal eyes is thickened so as to form a lens, 

 as appears to be the case in the trilobites. These peculiar eyes may be a direct inheritance 

 from the Hypoparia. 



ARCHICOPEPODA. 



Professor Schuchert has called my attention to the exceedingly curious little crustacean 

 which Handlirsch (1914) has described from the Triassic of the Vosges. Handlirsch 

 erected a new species, genus, family, and order for this animal, which he considered most 

 closely allied to the copepods, hence the ordinal name. Enthycarcinus kessleri, the species in 

 question, was found in a clayey lens in the Voltzia standstone (Upper Bunter). Associated 

 with the new crustacean were specimens of Estheria only, but in the Voltzia sandstone itself 

 land plants, fresh and brackish water animals, and occasionally, marine animals are found. 

 The clayey lens seems to have been of fresh or brackish water origin. 



All of the specimens (three were found) are small, about 35 mm. long without including 

 the caudal rami, crushed flat, and not very well preserved. The head is short, not so wide 

 as the succeeding segments, and apparently has large compound eyes at the posterior lateral 

 angles. The thorax consists of six segments which are broader than the head or abdomen. 

 The abdomen, which is not quite complete in any one specimen, is interpreted by Hand- 

 lirsch as having four segments in the female and five in the male. Least satisfactory of 

 all are traces of what are interpreted by the describer as a pair of long stiff unsegmented cerci 

 or stylets on the last segment. 



The ventral side of one head shield shows faint traces of several appendages which 

 must have presented great difficulty in their interpretation. A pair of antennules appear to 

 spring from near the front of the lower surface, and the remainder of the organs are grouped 

 about the mouth, which is on the median line back of the center. Handlirsch sees in these 

 somewhat obscure appendages four pairs of biramous limbs, antennae, mandibles, maxillulse, 

 and maxilhe, both branches of each consisting of short similar segments, endopodites and 

 exopodites being alike pedifortn. 



Kach segment of the thorax has a pair of appendages, and those on the first two are 

 clearly biramous. The endopodites are walking legs made up of numerous short segments 

 (twelve or thirteen according to Handlirsch's drawing), while the exopodite is a long breath- 

 ing and rowing limb, evidently of great flexibility and curiously like the antennules of the 

 same animal. The individual segments are narrow at the proximal end, expand greatly at 

 the sides, and have a concave distal profile. A limb reminds one of a stipe of Diplograptus. 

 Both branches are spiniferous. 



No appendages are actually present on the abdomen, but each segment has a pair of 

 scars showing the points of attachment. From the small size of these, it is inferred that 

 the limbs were poorly developed. 



This species is described in so much detail because, if it is a primitive copepod, it has 

 a very important bearing on the ancestry of that group and is the only related form that 

 has been found fossil. 



