40 Journal of Comparative Neurology. 



des Opticus fortsetzt : Die function des medienauges war urs- 

 priinglich, das Thier bezuglich der Richtung der Lichtquelle zu 

 orientiren; bei complicirterem Bau, schon bei den Calaniden, 

 hat es wahrscheinlich audi die Fahigkeit einer beschrankten 

 Bildperception. Am medianauge der malakostrakenlarven ist 

 der ventral Becher bisher nicht beobachtet, aber wohl audi 

 vorhanden. " 



In a Cypris obtained at Burlington, Ohio, each of the three 

 divisions of the median tripartite eye appears to be supplied 

 with a lens. 



DESCRIPTION OF PLATES. 



a}-, antennulary nerve ; a-, antennary nerve ; c, circum-oesophageal com- 

 missure; Did, mandibular nerve ; ntx^, nix'-, first and second maxillary nerves; 

 71, ventral chain ; W. S., infracesophageal ganglion ; O, optic nerve; S. G., su- 

 pracesophageal ganglion, 



All figures were drawn with an Abbe camera from sections of Cypris her- 

 ricJci, 



Fig. J. Transverse section of body in the region of the posterior portion of 

 the midgut. 



Fig. 2. Transverse section of median eye. 



Fig. 3, Longitudinal section of circum-oesophageal commissure. 



Fig. 4. Transverse section through sensory organ at margin of mouth [fig. 

 7 A.]. Only the bases of the hairs appear in the section and look like teeth, but 

 in adjoining sections the tips of the hairs can be demonstrated. 



Fig. 5. Transverse section of the chitinous muscular support which lies 

 immediately dorsad of the nervous chain. This is show in situ in fig. I. 



Fig. 6. Transverse section of body in the region of the lateral diverticles 

 of the midgut. 



Fig. 7. Longitudinal section through the infraiiesophageal ganglion. 



Fig. S. Longitudinal section through the brain at the level of the origin 

 of the circum-resophageal commissures. 



Fig. g. Median longitudinal section of the entire body. 



Fig. 10. Transverse section of brain, through the origins of the optic and 

 antennulary nerves. 



Fig. II. Longitudinal section through a portion of ventral chain showing 

 its intimate connection with the mesenteries. Seen in situ in fig. 9 B. 



