MK.MOIUS OK Tin; NATIONAL ACADEMY Ol' S( I KNCKS. 



'Ml 



iippt-r and lower portion, hut witliont :iny sliilk jiassin;; downwanl into the ccntiiil portion oltiic 

 brain. 



Dr. Saint Uoniy tlescrihes tliis body at lenjjtli under the nauie organe KtnttiJU' ponttrirur, 

 and says that it is situated on the very salient posUnior an<l uitpcr border of the brain, lorniin;; a 

 proniineiit projection above the punctuated mass of the cerebral lobes. It comprises a iirincipal 

 medullary portion and a cellular coverinj,'. It is formed of parallel altcrnat^^ clear and obs<;ure 

 banils. 



That this orjriin is apparently not homologous with the nitislirooiii liodies of insects appears 

 to l>e proved by the f:ict that it is single, not a paired organ. 



ant .gi in- 

 nv.vr. orjr. 



amL 



cer. g"an^ 



Fio. XIV.— A.horiMntal spction passing tliroucli tlieupiier jiartol thtbraiu of tliiacor]>ion (Bii(/i«.»oi;ci/a7iu*Amorx. )tlirongli tho lower 

 optic lobe or ganglion, eer. ijang., ctTobral ganglion ; I. eye n., lowtT eyt! nerve ; amb, anterior medullary brll of the lower optic ganglion : 

 in. b., middle medullary ball of the same j ped.. common peduncle of theoptic lobules ; parts of the stratified organ or body ; I. »(r., lower segment ; 

 u.tlr., upper segment ; aptir, anterior plate (lame) of the upper segment of the same; a. gang. «i., anterior ganglion-mass; on. 1. 1., antero- 

 internal lobule ; u>. org, principal medullary mass of the anterior segment of the wallet-shaped organ ; v. vessel (artery) ; B, longitudinal 

 (sagittal) section of the same passing through the union of the internal third with the miildlc third of the brain. Very young individual, 

 y XI diains.. <;. w. 6., principal glomerulated mass of the posterior segment of tho wallet-shaped organ ; principal medullary mass of tho an- 

 terior segment of the wallet-shaped organ ; ant. g. m.. anterior ganglion mass ; chel. lobe, ganglion innervating the first pair of appendages ; 

 e./., commissural fascia.— After Saint Kemy. 



In the scorpion (Fig. xiv, fitr. body) the stratified body dififers somewhat from that of spiders, 

 but is essentially the same. "But the most interesting feature abont it," says Saint Kemy, "is 

 the relation which exists between this organ and the optic lobe by the medium of the common 

 peduncle." Although the stratified botly of Arachuida is described and figured as unpaired, yet 

 in deference to the oi)inioii of Saint Kemy I i»rovisionally accept his view that it is the homologue 

 of the pair of peiluneiilated boilies of insects. I may add that it is a matter oi surprise to me that 

 M. Viallaues does not dwell more on the remarkable differences between the brains of Liinulus and 

 of the Arachuida, particularly the gieat dift'erences between the mushroom-bodies of Limulus and 

 their homologues in Arachuida, since he adopts the opinion that Limulus is an Arachiiidan. On the 

 other hand these striking ditlerences in the mori)hology of the brain tends to my mind to furnish 

 additional proof that Limulus is the representative of a ditierent class of Arthropods. 



