40 Descriptions of Preparations. 



For an account of the development of the vertebral column, see 

 Gegenbaur, Untersuchungen zur Vergleichenden Anatomic 

 der Wirbelsaiile bei Amphibien und EeptilieUj 1862, pp. 30 

 and 40. 



For the sexual peculiarities, see F. Pouchet, Comptes Reudus, 1 847, 

 pt. ii. p. 761. 



11. Common Perch (Perca Fhwiatilis), 



Injected and dissected so as to show its circulatory, nervous, digestive, respiratory, 

 and reproductive systems in situ. 



The part of the body posterior to the middle of the second dorsal 

 fin above and the anal fin below having been removed, an injection 

 was thrown into the dorsal aorta ; the walls of the body-cavity and 

 the opercular and branchiostegal apparatus were removed upon the 

 right side ; and the roof of the cranial cavity superiorly. 



In the triangular space bounded by the four bipectinate gills 

 of the right side anteriorly, by the liver posteriorly, and by the 

 middle line of the body in front ; we see the heart with its auricle 

 above, its ventricle below, and the bulbus arteriosus anteriorly. 

 Posteriorly to the liver we see the large single ovary, the upper 

 three-fourths of the right half of which have been removed, but, 

 owing to its extreme distention, without showing the transversely 

 lamellar arrangement of its more or less annular ovigerous in- 

 volutions. The upper end of the turgescent gland has interposed 

 itself between the under surface of the liver to the right and the 

 stomach, and the commencement of the small intestine and the 

 pyloric appendages to the left. A loop of intestine, which is a little 

 less in length than the half-length of the abdominal cavity, and 

 which, passing downwards from the commencement of the duo- 

 denum, contains the spleen in its concavity, is similarly concealed 

 from view by the distended ovary. 



Owing to the same cause only one of the three pyloric caeca is 

 visible in this preparation, the two which arise from the posterior 

 or concave aspect of the commencement of the duodenum having 

 been displaced to the left. The gall-bladder has been displaced 

 vipwards and to the right ; and may be seen occupying the apex 

 of an oval emargination in the free edge of the liver, which is 



