Miscellaneous. 235 



light and air. \n examining the snrface-mud of a shallow rain- 

 water |)0()1, in a reront t'xeavation in brick-clay, the author found 

 little cl.se but an abundance of minuti^ diatoms. He was not suffi- 

 ciently familiar with the diatoms to name the species ; but it re- 

 sembled Navicula rddtoaa. The little diatoms wore very active, 

 gliding hither and thither, and knocking the quartz-sand grains 

 about. Noticing the latter, he made some comparative measure- 

 ments, and found that the Navlcuhe would move grains of sand as 

 much as twenty-five times their own superficial area, and probably 

 fifty times their own bulk and weight, or perhaps more. — Proc. Acad. 

 Nat. SciPhilad. p. 113. 



On the Penplieral Nervous System of the Marine Nematoids. 

 By M. A. ViLLOT. 



The marine Nematoids possess well-characterized organs of sense, 

 consisting : — 1, of organs of touch, represented by numerous setae or 

 papillic distributed over the whole surface of the body, but par- 

 ticularly abundant I'ound the head and the genital orifice ; 2, of an 

 apparatus of vision, composed of two eyes, of rather complex 

 structure, situated on the dorsal surface towards the anterior ex- 

 tremity. The nature of these different organs ought not to be doubt- 

 ful ; but the fact is that their relations with the nervous system 

 have hitherto been very obscure. According to M. Marion * nervous 

 filaments penetrate obliquely " into the midst of the longitudinal 

 muscles to arrive soon at a fusiform, nucleolated cell, itself situated 

 at the base of a cuticular hair, and united with this hair by another 

 nervous thread which tenninates at the base of the hair." 



M. Biitschli, whose memoir is very recentf, has figured an analo- 

 gous arrangement ; but he states that he has not detected the fusi- 

 form cell described by the French writer. He expresses himself as 

 follows : — " Marion states with regard to his Thoracostoma setigerum, 

 that a little before the entrance into the setiile a fusiform ceU is in- 

 terposed in each of these filaments ; with the exception of ganglii- 

 form dilatations, which, however, seem to me to have no regular 

 occurrence, I have detected nothing which could be interpreted in 

 favour of this observation." 



In presence of these contradictory assertions it became necessary 

 to undertake fresh researches, and to subject those which had been 

 made to the check of the experimental method. Hence my atten- 

 tion was directed most particularly to this point when, in the month 

 of May last, I commenced my investigation of the Helmintha of our 

 shores, in the laboratoiy of Professor de Lacaze-Duthiers. Now it 

 appears from my numerous observations made at Koscoff upon living 

 individuals, and repeated at Paris upon my preparations, that the 

 two naturalists whom I have just cited have been deceived by false 



* " Additions aiix reclierches sur les N^matoides libres du Golfe de 

 Miir-eille," Ann. Sti. Nat. Zool. 5« s^rie, torn. xix. p. 13, pi. xx. fig. 1. 



t Zm- Keuntniss der freilebenden Nematoden, iusbesondere der des Kieler 

 Ilafens, p. 8, pi. iv. fig. 19, h (1874). 



