154 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



and, crossing its former course nearly at right angles, proceeds along the upper part of the 

 side, getting lower as it approaches beneath the dorsal, to terminate at the caudal. There arc 

 also two short transverse lines j one across the snout, connecting the loops ; another across the 

 nape, connecting the two main lines after they have assumed the usual direction. 

 Colour.— "Beneath snow white. Above dark brownish- black, this colour forming a series of broad 

 oval rings, one within another ; the outer and largest ring includes nearly the entire surface of 

 the back and sides. The upper surface is, in addition, marked with round spots of a darker 

 shade. Pectoral and dorsal fins yellowish brown. Iris, inner edge clouded with orange; 

 pupil dark green-blue."— D.— In its present state, there is no indication of the rings noticed 

 above. The spots, which are small, and cover nearly the whole head, back, and sides, appear 

 also sparingly on the basal half of the caudal, but not on any of the other fins. 



Habitat, Galapagos Archipelago. 



This species was taken by Mr. Darwin at Chatham Island, in the Galapagos 

 Archipelago. He observes in his notes that it makes a loud grating noise. It is 

 remarkable for the great tortuosity of the lateral line. The form of the nostrils is 

 also rather peculiar. 



4. Tetrodon angusticeps. Jen. 



Plate XXVIII. 

 T. supra obscure viriclis : capite oblongo, subcompresso, spatio interoculari multum 

 contracto : corpore infra ventricoso, ubique lesvissimo, duobus, in summo dorso, cirris 

 cutaneis parvis adomato : maxillis suboequalibus : naribus tubulosis, indivisis, aper- 

 turis duobus lateralibus : lined laterali in capite tortuosissima : pinna dorsali omnino 

 ante pinnam analem ; caudali cequali. 



D. 8; A. 7; C. 9; P. 15. 

 Long. unc. 9. lin. 3. 



Form.— Rather more elongated than the last species ; especially in regard to the head, which is also 

 more compressed upwards, reducing the space between the eyes to a narrow channel, much 

 hollowed out, and not exceeding one diameter of the eye. Body inflatable, every where quite 

 smooth. Jaws nearly equal, the upper one perhaps a very little in advance. Nostrils tubular, 

 with two lateral apertures, somewhat similar to those of the last species, but more elevated. 

 Lateral line similar, taking the same windings on the head. A little behind the transverse 

 line on the nape, and nearly above the attachment of the pectoral, are two small skinny 

 appendages : there is also a very minute one on each side of the tail, but none elsewhere. 

 Dorsal wholly before the anal. Caudal square. 



Colour.—" Above dull green : base of the pectorals and dorsal black ; a white patch beneath the 

 pectorals." — D.— The colours must have very much altered from the action of the spirit, as it 

 now appears of a nearly uniform reddish brown, only paler beneath. 

 Habitat, Galapagos Archipelago. 



Another apparently undescribed species of this genus, taken by Mr. Darwin 



at the same place as the last. He observes in his notes that it is inflatable. 



