526 
Nachdruck verboten. 
Salpa and the Phylogeny of the Eyes of Vertebrates. 
By Maynarp M. Mercatr, Oberlin College. 
Nearly a year ago there appeared an interesting paper by REDI- 
KORZEW!) in which he described the anatomy of the eye of several 
species of Salpa and, on the basis of the conditions described, made 
suggestions as to the origin of the eyes of vertebrates. The anatomical 
descriptions I do not wish to criticise here. Such discrepancies as there 
are between his account and those previously published by GÖPPERT?) 
and by myself?) can readily be noticed by those especially interested. 
But it may be well to write a few words in regard to the evidence 
which the eyes of Salpa and of tunicate larvae are supposed to give 
as to the phylogeny of the eyes of vertebrates. 
REDIKORZEW interpreted the eyes of Salpidae as composed of 
three bilaterally paired groups of optic cells, and suggested that in this 
condition in the Salpidae we have a confirmation of the conclusions 
Locy has drawn from the presence of bilaterally paired pits in tbe 
medullary plate of vertebrates, from the first three successive pairs of 
which develop the lateral eyes, the epiphysis and the paraphysis. 
Locy’s observations are of great interest and his conclusions seem 
to be not improbable, but that the condition of the eyes of Salpidae 
lends any support to these conclusions it is impossible to believe for 
several reasons. 
In the first place the eye of Salpa is not made up of a series of 
bilaterally paired structures; nor does it arise in the development of 
the embryo or the buds by a fusion of lateral halves as REDIKORZEW 
supposes. In one species, Cyclosalpa pinnata, the eye of the chain form 
does show one pair of considerable enlargements upon the continuous 
hörseshoe-shaped organ. In the solitary forms of several species also 
there are enlargements of the ends of the horseshoe. Furthermore we 
1) W. Repıkorzew, Ueber das Sehorgan der Salpen. Morphol. 
Jahrbuch, Bd. 34, Heft 2, Nov. 1905. 
2) W. E. Görrert, Untersuchungen über das Sehorgan der Salpen. 
Morphol. Jahrb., Bd. 19, 1892. 
3) M. M. Mrrcatr, The Eyes and Sub-neural Gland of Salpa. 
Johns Hopkins Univ. Morphological Monographs, Vol. 3, 1893, Part 4. 
