Miscellaneous. 235 
light and air. In examining the surface-mud of a shallow rain- 
water pool, in a recent excavation in brick-clay, the author found 
little else but an abundance of minute diatoms. He was not suffi- 
ciently familiar with the diatoms to name the species; but it re- 
sembled Navicula radiosa. The little diatoms were 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 Navicule 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. Sci. Philad. p. 113. 
On the Peripheral Nervous System of the Marine Nematoids. 
By M. A. Viztor. 
The marine Nematoids possess well-characterized organs of sense, 
consisting :—1, of organs of touch, represented by numerous sete or 
papille distributed over the whole surface of the body, but par- 
ticularly abundant round 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 terminates at the base of the hair.” 
M. Butschli, whose memoir is very recent}, 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 setule a fusiform cell 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 laboratory of Professor de Lacaze-Duthiers. Now it 
appears from my numerous observations made at Roscoff 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 aux recherches sur les Nématoides libres du Golfe de 
Marseille,” Ann. Sci. Nat. Zool. 5¢ série, tom. xix. p. 13, pl. xx. fig. 1. 
+ Zur Kenntniss der freilebenden Nematoden, insbesondere der des Kieler 
Hafens, p. 8, pl. iv. fig. 19, 6 (1874). 
