480 Miscellaneous. 



same family. Tlie elements of the protective covering in the 

 flatter are modified marginal spines ; 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 tv\ o structures is dissimilar. Hiantopora must 

 therefore be the type of a distinct family group. 



[To be coutinued.] 



MISCELLANEOUS. 



On tlie Nfvvous System of Monocotylidae. 

 By M. G. Saint-Remy. 



Among the IVistomete, the nervous system of the Tristomidd; is 

 well-known, thanks to recent researches, in particular the labours 

 of Lang and Monticelli. No precise observations have hitherto 

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

 types — Pseudocotylc squatlnce and Microhotlir'mm apiculatum *. 



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

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

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

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

 they anastomose. The nervous system of Pseudocotyh squatince 

 most nearly resembles this type. The braiu is a thick band, in- 

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

 the vestibule ; it gives rise to tive 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 itself in the parenchyma, 

 above the mouth : it is the horaologue of the nerves of the Tristomiau 

 frontal lobe, the internal nerves of Monticelli, The second pair 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 

 suckers (median nerves) of the Tristomidcp. The fourth corresponds 

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

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

 Tristomum, 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 



* These investigations were made U])on animals collected at the Roscoff 

 laboratory, where Prof. Lacaze-Duthicrs was good enough to accord to 

 lis the most liberal hospitality. 



