162 BRODE. [Vou. XIV. 
or largest girdle. These organs vary in size, but he does not 
describe any arrangement of organs in rows longitudinally. 
Polychaetes. —In this group of annelids we have the well- 
known “ lateral organs”’ of capitellids which have been described 
at length by Eisig.1 These number one pair to a segment and 
are situated in the lateral-line region of the body, and in a band 
passing through the setae. 
Similar organs have been found by Meyer? in Polyophthalmus, 
and in addition to these, in this form, there are sense organs 
resembling eyes on twelve of the body segments. ‘These are 
in a line with the other organs, but are situated near the 
anterior border of the segment. 
Eisig finds in addition to the “lateral organs,’ which are 
highly developed, some organs of a simpler character which are 
scattered diffusely over the body. These he calls ‘cup-shaped 
organs.” He thinks that for the present we can assert no rela- 
tionship between these two kinds of organs excepting the fact 
of their origin from the epidermis. 
Leeches. — The metameric sense organs, sensillae, of leeches 
have been described by Whitman.® In Clepsine there is a band 
of fourteen organs around the anterior portion of every seg- 
ment. These organs are so situated as to form longitudinal 
rows extending the whole length of the leech. In six rows the 
organs are larger than in the others. In Clepsine the organs 
of the median dorsal row gradually change from tactile to visual 
organs in the anterior segments. 
Vertebrates. —In fishes and larval batrachians we find scat- 
tered “cup-shaped organs,” and also more highly developed 
organs which are arranged in certain definite lines, and in young 
forms often are arranged metamerically. These organs are 
considered by some writers to be essentially the same, —the 
variations being due to difference in development rather than 
to a structural unlikeness. The suggestion has been made by 
several workers that there is a homology existing between these 
1 See Bibliography, p. 173, Nos. 8 and 9. 
2 Eduard Meyer, Zur Anatomie und Histologie von Polyophthalmus pictus 
Clap., Archiv f. mikros. Anat., Bd. X XI, 1882, pp. 797-799. 
8 C. O. Whitman, The Metamerism of Clepsine, Festschr. f. Leuckart, Leipzig, 
1892, pp. 385-395: 
