480 Miscellaneous. 



same family. The elements of the protective covering in the 

 latter are modified marginal spinas ; in the former they are 

 special processes given off from the walls of the cell. These 

 are not morphological equivalents, whilst the general cha- 

 racter of the two structures is dissimilar. Hiantopora must 

 therefore be the type of a distinct family group. 



[To be coutinued,] 



MliSCELLAXEOUS. 



On the SfTvous System of Monocotylidse. 

 By M. G. Saixt-IJemy. 



Among the Tristomece, the nervous system of the Tristomkhn is 

 well-known, thanks to recent rcsearche?, in particular the labours 

 of Lang and Monticelli. No precise observations have hitherto 

 been made on the Monocoiylidce, of which we have examined two 

 types — Pseiidocotyle squatince and Microhothr'mm apicidatuin *. 



We know that, among the Tristomidce, the brain, situated altove 

 and in front of the pharynx, sends out six pairs of nerves, three in 

 front and three behind (lateral nerves), of whicli the two outermost, 

 ventral in position, extend as far as the posterior sucker, where 

 they anastomose. The nervous system of Fseudoco(>/le sqiuitino' 

 most nearly resembles this type. Tbe brain is a thick band, in- 

 curved during growth, and situated in front of the pharynx, above 

 the vestibule ; it gives rise to five pairs of anterior nerves, and 

 behind to two or perhaps three pairs of lateral nerves. The first pair of 

 anterior nerves is large, arises directly against the median line in 

 the upper region of the brain, and loses it^clf in the parenchyma, 

 above the mouth : it is the homologue of the nerves of the Tristomian 

 Irontal lobe, the internal neiwes of Monticelli. The second ]>air is 

 very slender and of little importance ; the third is constituted by 

 two branches which start one from each exterior angle of the brain, 

 and lose themselves outside: they represent the nerves of the 

 Slickers (median nerves) of the Tristoniid<r. The fourth corresponds 

 to the third pair of the latter: it is formed of two strong branches, 

 Avhich pass forwards and inwards to unite in the median line, as in 

 2'ristoiniivi, but remain here -nithout contact with the other anterior 

 nerves. Lastly, the fifth pair is represented by two little accessory 

 threads of no importance. 



As regards lateral nerves, we have found two pairs of strongly 



* Those investigations ^verc made uiuui animals collected at the KoM\'ff 

 laboratory, where VivL Laeaze-Duthiers was good enough to accord to 



u^ the nu'Sl liberal hi'S]>italily. 



