Prof. E. Claparéde on the Structure of the Annelida. 347 
sages* in which I mentioned these organs, and cited an analo- 
gous observation of M. Keferstein; but by a singular mistake 
he makes us describe convolutions of blood-vessels, whilst we 
speak very positively of glandular coils. Such a confusion is 
hardly possible ; for the passage relates to Nereids, in which the 
coils in question are colourless, whilst the vessels are of a fine 
red colour. M. Kolliker was the first to discover, in Sphero- 
dorum peripatus, that each coil of the glomerules contained in 
the spherical appendages opens outwards by a separate pore. 
This observation has just been repeated by M. R. Greef in 
Spherodorum Claparedii +. 
Muscular System. 
The muscles of the Annelida present extraordinary variations 
in their histological structure, as I shall have more than one 
occasion to show in the course of this memoir. Sometimes they 
are composed of fibres with parallel edges and entirely destitute 
of nuclei, sometimes, on the contrary, of fibre-cells furnished 
with large nuclei. 
The existence in’ the Annelida of fibre-cells of a muscular 
nature has indeed been entirely denied by M. Schneider}. But 
although this naturalist may be right in the immense majority 
of cases, we shall see that this rule is liable to some exceptions 
(pharynx of certain Nerezdea, tentacles of various Terebellea, &c.). 
Sometimes the muscular fibre separates into two distinct layers 
(one axial, the other cortical), as M. Leydig was the first to 
remark§. Nowhere is this structure so distinctly shown as in 
Nephithys. Wastly, in some Annelida, as M. de Quatrefages very 
justly indicates, the muscular system undergoes a remarkable 
simplification, in the loss of its fibrillar structure. Sometimes 
we find, in place of the muscles, nothing but a contractile proto- 
plasm with nuclei dispersed through it. Of this we shall indi- 
cate some examples hereafter. 
The ‘ Histoire Naturelle des Annelés’ indicates between each 
segment a sort of tendinous raphe upon which the muscular 
fasciculi are inserted ||. These raphes have no existence. It is 
easy to ascertain, from longitudinal sections of Annelida, that 
the longitudinal fasciculi are continued without any interruption 
throughout the length of the worm. This has already been 
seen and described by De Blainville, Delle Chiaje, Rathke, 
Meckel, &c. 
* Beobacht. &c. p. 52. 
+ See ‘Annals’ for July, vol. xx. p. 4 e¢ seq. 
t “ Ueber die Muskeln der Wiirmer, &c.,’’ Miiller’s Archiv, 1864, p. 590, 
§ “Ueber Phreoryctes Menkeanus,” Archiv fiir mikrosk. Anat. Band i i, 
p. 249. 
|| This notion, however, is revived from Cuvier, 
