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Show 1902.] PLECTOGXATHOUS FISHES. 299 enlarged tubercles more prominent. Soft dorsal and anal similar, rounded, their longest ray half as long as the dorsal spine. Pectoral scarcely longer than the gill-opening. Caudal rounded. Caudal peduncle deeper than long, with two pairs of barbs on each side as in the preceding species. Ventral spine moderate, barbed. Scales as minute granules. Greyish, with rounded lighter (? light blue) spots on the sides of head and body. Upper part of head and body, above a line from the tip of snout to the eye and thence to the last dorsal ray, brown. Lower part of the body with a similar brown area. Fins immaculate. A single specimen from Tahiti, 175 mm. in total length. Very closely allied to the preceding species, differing chiefly in the more concave snout, more strongly armed dorsal spine, and colour. P se u d om o n a c an th u s d e g e n i , n. sp. (Plate X X IV . fig. 1.) Depth of body equal to length of head, 3 times in the total length. Snout slightly convex, about 3| times as long as the eye-diameter, which is equal to the interorbital width. Gill-opening about equal in length to | the eye-diameter, its upper end below the hind margin of the eye. I). II, 34. A. 33. Dorsal spine above the hind margin of the eye, without barbs, its length 21- in that of the head ; second spine scarcely visible. Soft dorsal and anal similar, rather elevated anteriorly, the rays increasing in length to the eighth or ninth, which is the longest and equal to half the length of the head, thence decreasing to about the twentieth, the rest subequal. Pectoral almost as long as the dorsal spine. Caudal rounded, more than half the length of head. Caudal peduncle longer than deep. Scales minute, shagreen-like. Ventral spine small. Greyish, with blue spots on the sides of the head and anterior part of the body, and on the caudal peduncle. Some faint oblique blue lines on the sides between dorsal and anal fins. Fins green. A single specimen, 190 mm. in total length, from Melbourne Market, Australia. Mr. Degen sent with the fish a drawing showing the colours when fresh. This species is closely allied to Pseudomonacanthus modestus, Gthr., ayraudi Gthr., and septentrionalis Gthr., which it resembles in physiognomy and in the shape of the fins, but all these have distinct barbs on the dorsal spine. T etrodon in e rm is Schlegel. This species was considered by Giinther to be a variety of the Atlantic T. Icevigatus, and the descriptions of Schlegel and Day (Fishes of India, p. 701, pi. clxxx.) have not sufficiently pointed out the features which distinguish it from that species, the most noticeable of which are as follows:-In T. inermis the body is much broader and deeper in proportion to its length, there is no distinct lateral fold in the abdominal region, and the spines on |