XXXvi JoiK.NAl, OI- C('Mr.\K.\'ll\E N El" K( >!,( x; V . 



The separation of the hrain from the general ectoderm is later than 

 that of ganglia. There is a peculiar grouping of the nuclei, as that found 

 in the retinal portion of the eye, in the nervous system before it is 

 separated from the general ectoderm." 



Brain ok the Horse-shoe Crah.(I) 



The brain of the adult is made up of three pairs of lobes, enveloped 

 in thick masses of chromatic cells. The uppermost are the pair of 

 lateral eye lobes, widely separated from each other on the top of the 

 brain and give off well-developed nerves. 



The nerve cells appear to arise from the chromatic cells. " The lobe 

 just below the middle is seen to be imbedded in the dense ring or ruffle- 

 like masses of deeply-stained chromatic cells, which we have called the 

 ' nucleogenous bodies.'" The brain of Limulus differs from that of 

 Arachnida in sending no nerves to the first appendages, and is homo- 

 logous with the forebrain of spiders, according to Patten. " The nerves 

 which give rise to the first pair of appendages do not arise from the 

 base of the brain, but the ganglion cells giving rise to them are situated 

 entirely outside of and behind the brain proper." The lobes of the 

 median-eye nerves are small and slender and not much swollen, and lie 

 far below [ventrad of.''] the plane of the lateral-eye lobes. Their form 

 and size indicate that they have atrophied. 



There is, below the median-eye lobes, a pair of minute lobes, each 

 sending off a bundle of fibrilke backwark [caudad.^J toward the cerebral 

 commissure, which may possibly give rise to a pair of tegumental or 

 haemal nerves. No traces were discovered of Patten's nerves of the 

 median eye of the first segment." 



The third pair of (major) lobes are the cerebral lobes. These are 

 verv irregular in outline, slender and apparently shrunken, and very 

 different from the full well-developed sub-sperical shape of those of 

 arachnids. 



Prof. Packard differs from Viallanes in believing that there are 

 "but three preoral segments of the head " of insects. He considers that 

 the differences are of sufficient importance to forbid the union of the 

 Podostomata with the arachnids. 



Edinger's Text-Book on the Nervous System. (2) 



It is a pleasure to note the publication in this country of a con- 

 densed manual of the anatomy of the human brain by so eminent an 

 investigator as Dr. Edinger. It is equally pleasant to note that the 



1 Packard, Alpheus S., "Farther Studies on the Brain of Limulus Polyphemus," 

 Zool. Anzeiger, XIV, 361, pp. 129133. 



2 Edinger, Ludwic, " Twelve Lectures on the Structure of the Central Nervous 

 System, for Physicians and Students" Second revised edition, with 133 illustrations. 

 Translated by Willis Hall Vittum ; edited by C. Ei gene Riggs Philadelphia : F. A. 

 Davis, 1890. 



