G04 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the hypodermis, ami arc not strictly conncctivo-tissuc fibres. The 

 fibrous strands and sinew-plates produced within the chitinogenous 

 cells arc micro-chemically distinguishable from the superficial chitin 

 of tho cuticle. The mesoderm connective-tissue elements are then 

 discussed, and the special modification of theso by the accumulation 

 of fatty globules within the protoplasm. The various distribution 

 of the fatty cells and tho parts that they seem to discharge, for instance, 

 in aiding the chitinized basal membrane of tho hypodermis cells to 

 form the sinew-plates aro described at length. 



V. Musculature. — Two dorsal muscles extend along tho blood- 

 vessel, and two ventral along the nerve-cord ; the external bundles 

 of tho latter diverge dorsally in the segments behind the genital 

 region ; the myomere of the last abdominal segment is well defined 

 from the anal piece (not in Artemia), but several long muscle-cells 

 pass into the latter. The lateral-dorsal, and the median-ventral groups 

 of transverse muscles, and the disposition of tho component bundles in 

 each appendage-bearing segment are described, and compared with 

 the homologous musculature of the maxillae, and with the more 

 complicated modifications in the second antennary and mandibular 

 segments. Special attention is directed to the interesting connection 

 between the muscles themselves and with the integument, by means 

 of numerous sinewy connective fibres which distribute the strain over 

 a large surface of insertion. 



VI. Nervous system and sense-organs. — BrancMpus, like other 

 Phyllopoda, affords beautiful illustration of the rope-ladder-like nerve 

 chain, produced by the marked distance of the two ganglionated 

 cord and the consequent breadth of the transverse commissure. 

 The position of tho antennary ganglia on the oesophageal ring and 

 the persistent separation of the mandibular and maxillary ganglia, 

 are also regarded as expressions of primitive characters. With the 

 exception of that connecting the mandibular ganglia, the commissures 

 of the above ganglia are double, as are also those of the two pairs 

 of small ganglia in the genital segments. Prof. Claus gives reasons 

 for regarding the primary cerebral ganglion mass as referable to the 

 apical disc of Loven's larva, while the ganglia of the segments owe 

 their origin to paired thickenings of the hypodermis. He gives a 

 minute description of the structure and histology of these supra- 

 cesophageal nervous structures, of the sensory setas on the antenna), 

 &c, and of a hitherto unobserved sense-organ, similar to that structure 

 in Cladocera first described by Leydig as " Nackenorgan." 



VII. The stalked eyes. — Prof. Claus emphasizes what even 

 Carriere in his recent work on the comparative anatomy of optic 

 organs overlooks, that the compound lateral eyes of Branchipus are 

 seated on movable stalks, and indicates the great interest of their 

 relatively simple relations as elucidating the more complex structures 

 and connections in the eyes of Decapods and Stomatopods. After 

 noting the perfect homology of the eyes of Branchipus with those 

 of these higher types, and reasserting his previously maintained 

 derivation of these organs from parts of the head which have become 



