332 PKOF. M. M. HARTO& OlS" THE 



The Morpliology of Cyclops and the Eelations of the Copepoda. 

 By Marcits M. Habtog, D.Sc, M.A., F.L.S., Prof. Nat. 

 Hist., Queen's College, Cork. 



[Abstract *.— Bead 19th June, 1884.] 



This paper opens with a full anatomical description of Cyclops 

 hrevicornis, Claus, worked out in great part by the method of 

 sections. The chief new points made out are as follows: — In 

 the skeleton a free entosternite is demonstrated in the maxillary 

 region, and homologized with the tendon of the adductors of the 

 valves of the bivalve Entomostraca. A large posfcmaxillary apo- 

 deme in all Copepoda gives attachment on either side to the 

 great flexors of the trunk. A spring arrangement is shown to 

 relax the flexed male antennule used as a clasper. Pore-canals, 

 cells, or cutaneous glands each receive a nerve-fibre at their 

 proximal end. The hypodermal cells have a polygonal outline. 



Under the mesoblastic tissue, Erie's discovery of amoeboid 

 coelomic corpuscles is confirmed. The apparatus of deglutition 

 is fully described, and the author has made out a pair of salivary 

 glands in the epistoma, whose ducts join to open on the back of 

 the labrum by a median pore. In connection with the alimen- 

 tary canal, the mechanism of circulation and anal respiration is 

 described, the eflSciency of the latter being strongly maintained. 



The kidney, or " shell- gland," is shown to be a simple, much- 

 coiled tube, with chitinous lining, opening at the base of the 

 outer maxilliped. Incidentally the presence of this organ is 

 noted in several divisions of the marine Copepoda, and the author 

 suggests that it is identical with the " antennary gland " of 

 similar structure of the Nauplius larva, which would have shifted 

 its aperture. 



A full description of the nervous system follows. The pre- 

 sence of ganglion-cells in the circumoesophageal cords is noted, 

 and used as an argument for regarding the (2nd) antennae inner- 

 vated therefrom as oral rather than postoral appendages. 



The presence of corneal facets to the lateral ocelli is noted, 

 and an attempt is made to connect what the author has described 

 elsewhere as auditory organs with the unicellular pore-canal 

 glands. 



The views of Gruber on the reproductive organs are confirmed, 



* This paper will appear in the Transactions with appropriate illustrations. 



