148 
ZOOLOGICAL LITERATUKE. 
As regards Leydig’s view that this system is an organization 
appertaining to special organs of touch, the author admits that, 
, sometimes, it may be made secondarily subservient to tliis pur- 
pose; but its proper function is the secretion of some fluid 
which is poured forth from the skin as an excretion. However, 
it is certain, and has repeatedly been proved by direct experi- 
ments, that the slimy mucus whicli lubricates the body of many 
fishes is not formed by this system. — The presence of this 
system of the lateral line in Lepidosiren annectens is important 
for determining the position of this animal in the division of 
Vertebrata, as this organ is possessed by almost all fishes, and 
entirely absent in the Amphibians. 
I Hollard, H. Recherches sur la signification homologique de 
quelques pieces faciales des poissons osseux. Ann. Sc. Nat. 
1864, i. January (pp. 5-19, with a plate). 
Holla RD, H. De la signification anatomique de Pappareil 
operculaire des poissons et de quelques autres parties de 
leur systeme solide. Ibid. April (pp. 241-256, with a 
j plate) . 
I Hollard, H, Du temporal et des pieces qui en represen tent 
1 les elements dans la serie des animaux vertebres. Ibid, 
j June (pp. 359-376, with a plate). Abstract in Compt. 
I rend. Acad. Sc. Paris, 1864, i. March 21 (p. 528). 
Professor Hollard has published a series of papers, in which 
he gives the result of his most exact researches into the deve- 
lopment and homologies of the bones between the temporal 
region and the mandible, especially as they appear in the class 
of fishes. He deduces his homological interpretations entirely 
from the development of the different pieces ; and their correct- 
V ness will depend on the question whether development is a sure 
^ test for homologies or not. 
In the first paper, Ann. Sc. Nat. 1864, i. p. 6, he examines that group of 
hones of fishes which are comprised under the names of mandihulary suspen- 
sorium, and temporo-maxillary or tympanic group. He shows (in embryons 
of some Salmonoid) that the five bones composing that group [os tempoi'ale 
(Cuv.), os symplecticum (Cuv.), os jugale (Cuv.), os tympanicum (Cuv.), 
pr(Bopei'cvlum'\ are formed out of two primordial cartilages. The anterior 
serves for the suspension of the mandible, and is the base for the formation 
of two of the bones named, os jugale and os tympanicum, which consequently 
are the homologues of the os quadratum of Birds. The posterior serves for 
the suspension of a complex hyoid arch and for the attachment of the oper- 
cular apparatus, and is therefore the homologue of a much developed styloid 
bone, which is composed of three distinct pieces, viz., prceoperculam, os sym- 
plecticum, and os temporale (Cuv.). But when we consider Cuvier’s tempo- 
rale as a part of the styloid bone, it follows that it is not homologous to the 
