No. 2.] LINE SYSTEM OF BATRACHUS TAU. 227 



At a point midway between the anterior and posterior nares 

 the infraorbital line branches. One division extending along 

 the border of the ma.xillary may therefore be called the maxil- 

 lary branch, the other being the suborbital portion of the main 

 line (Fig. i). There are seven organs in this maxillary branch, 

 five being free organs and two enclosed in a short canal 

 (PI. XX, Fig. 22). The suborbital portion consists of eight 

 free organs, bordering the lower half of the orbit (Figs. 22 

 and 23). 



At the outer angle of the eye there are two free organs 

 (9, 10) continuing the line of the infraorbital and correspond- 

 ing to the otic portion (15, 16) as seen in Amia. (Compare 

 PI. XX, Figs. 21 and 22.) In the temporal portion of the line 

 there is a single organ (11) enclosed in a canal (Fig. 22). The 

 infraorbital line is continued on to the body as the dorsal line 

 of free organs (Figs. 22 and 24). 



2. Supraorbital line. — There are seven organs in this line. 

 The first, a free organ, is situated near the median line, a little 

 anterior to the opening of the posterior nares (PI. XX, Fig. 22). 

 Organs 2-6 are enclosed in a canal, while the seventh is a free 

 organ occupying a position apparently outside the line and on 

 the top of the head (PI. XVII, Fig. 2 ; PI. XX, Fig. 22). There 

 is evidence of the presence of the supra-temporal cross-commis- 

 sure, although the canal seen in Amia is wanting in Batrachus. 

 In one specimen, 12 cm. in length, the line was conspicuous, 

 as two extra organs were present in this region of the head. 

 In PI. XX, Fig. 22, st.com., the position of the line is indicated. 

 The middle pit line of Amia may be represented in Batrachus 

 by the organ just dorsal to the temporal canal (Fig. 22, m.l.). 



Four organs on the top of the head, extending on to the 

 trunk each side of the first dorsal fin, constitute what is desig- 

 nated by Allis as the dorsal body line in Amia. (Compare 

 Figs. 21-23.) 



3. Opcrctdo-tnandibidar line. — The first organ of this line is 

 found on the lower side at the symphysis of the mandible. 

 There is no commissural connection here between the two 

 sides of the head. Four organs, which never become enclosed 

 in a canal (Fig. 3), occupy a depression which appears as an 



