1710 
ON SIMPLE STRIATED MUSCULAR FIBRES. 
the Phylactoliemata, though this is denied by Nitsche * and by 
Schwalbe f. They occur also in the occlusor muscles of the avicu- 
laria of the Cheilostomata (^Diachoris, Bugula), in which their 
occurrence has not, so far as I can ascertain, been noticed hitherto. 
The striation is somewhat similar to that already noticed as 
occurring in the muscles of the pedicellarise of Sea-Urchins ; but 
is more strongly marked, being faintly visible in the living state 
and coming out with great distinctness in specimens treated either 
with Heidenhain’s hsematoxylin or by means of the gold-formic 
acid method. Each fibre has a single small intrinsic nucleus. 
The muscles of Salpa were described by Eschricht f as more 
strongly striated than those of any Arthropod or Vertebrate. I 
have not succeeded in making out striated fibres in the transverse 
muscular bands of Salpa or of Doliolum, but this is probably due to 
the condition of my specimens. 
In the heart of Salpa, Dogiel describes well-marked striated 
fibres, and in Cynthia a similar tissue was observed by Schwalbe ; 
1 find the same to hold good of ClavelUna — the striations in this 
case being very faint. It seems most likely that these instances of 
striated fibres in the Urochorda will prove to be examples of the 
compound type. 
* “ Beitrage zur Anatomic u. Entwickelungsgeschichte der Phylactolaren 
Susswasser Bryozoen.” ‘ Archiv von Reichert u. du Bois-Reymond,’ 1868. 
t “ Ueber den feineren Ban der Muskelfasernwirbelloser Thiere.” ‘Archiv 
f. Mikro. Anat.’ V. p. 205 (1869). 
X “ Anat.-Physiol. Unters. liber die Salpen.” ‘ Miiller’s Archiv.’ 1841. 
