DISCUSSION OF SPECIES AND THEIR DISTUIBUTION. 475 



PERISTEDION TKUNCATUM, Gi ntiiek. 

 I'erislelhiis truncal iim. (ii'NTJiEK, Challenger Rejuiit 1, I'art (!, 1880, 7, )il. II, fig. A. 



The leii.ytli of the pieoibititl processes is eoiitaiued twice aud tliiee-fonrtlis in the dis- 

 tance between their extremities and tlie anterior margin of the orbit. Iiiterorbital s])a(!e 

 deeply eoucave, with a depressed smooth groove aloug the middle; a minute spine on the 

 base of each preorbital jirocess, but no other ou the upper surface of the snout; lower jaw 

 with enormous barbels, the longest being fringed. The i)reoperc,ular ridge does not extend 

 beyond the liind margin of the bone, and is not produced into a spine; also the opercular 

 ridge terminates in a short and truncated projection. Each scute of the body with a 

 hooked xpinc. Each of the bony plates between the ventral tins is not <iuite twice as long 

 as broad. Kose-colored, with small, iri'egular brownish spots on tlic up])er i)arts. 



Radial formula: D. vii, 19; A. 20; L. hit. 32. 



The type of this species, a specimen (ii inches long, was taken by the Cknllenger at 

 station 122, off the coast of Pernambuco, in 30 or S.^O fathoms or in some intermediate depth. 



Dr. Giinther, thcmgh, unwilling to commit himself as to the bathybial habitat of any of 

 the forms collected by the Cludhnycr at station 122, ]>referring to include them all in his 

 report upon the shore-lishes, has nevertheless described one of the fishes there taken, under 

 the very signilicant name ot Bathi/anthias. 



Suborder T^ENIOSOMI. 



Taniosomi, Gii.i., Americau Naturalist, XXI, 1887, 86; xxiv, 1890, 481. 



Teleocephals with the scajmlar arch subnormal, ]»isttem])oral undivided and closely 

 applied to the back of the cranium, between the eiiiotic and ptcrotic, or upon the i)arietal; 

 hyijercoracoid perforate at or near the margin; cranium with the epiotics enlarged, (!n- 

 croaching bat^kward and juxtaposed behind, intervening between the exoccipitals and 

 supraoccipatal; prootic and the opisthotic represented chiefly by the enlarged prootic; 

 suborbital chain imperfect; the scapular bones separated by intervening cartilaginous ele- 

 ments; the hypo]iharvngeals styliform and ])arallel with the l)rauchial arches; epipharyu- 

 geals in full number (4 i)airs), and mostly coni|)ressed; the dorsal lin composed of inarticu- 

 late rays or spines, separable into lateral li:d\es, and the ventrals (when present) sub- 

 brachial. 



A myodome may be luesent or absent, none being developed in the Itegalecidas but 

 one being distinct and supi>Iemented by a dichost in the Trachypterida'. ((lill.) 



"The ribbon tishes," says (iiinther, '• arc true deep-sea fishes, met with in all parts of 

 the oceans, gcnei'ally found when floating dead on the surface, or thrown ashore by the 

 waves. Their body is like a band, specimens of from l.T to 20 feet long being from 10 to 

 12 inches deep and about an inch or two broad at their thickest part. The eye is large 

 and lateral; the mouth small, armed with very feeble teeth; the head deep and short. A 

 high dorsal lin runs along the whole length of tlu^ back, and is supported by extremely 

 numerous rays; its foremost portion, on the head, is detached from the rest of the tin, and 

 coini)t)sed of very elongate flexible spines. The anal lin is absent. The caudal tin (if pre- 

 ser\ed, which is rarely the case, in adult specimens) has an extra-axial jiosition, l)eiug 

 directed nxtwards like a fan. The ventrals are thoracic, either comj)osed of several rays or 

 reduced to a single long filament. The coloration is generally silvery, with losy tins. 



"When these tishes reach the surface of the water the ex])ansion of the gases within 

 their l)o(!ies has so loosened all the parts of their muscidar and bony system (hat they can 

 be lifted out of the water with difficulty only, and nearly always poilious of the body and 

 tins aie broker, and lost. The bones contain very little bony malter, are very ])orous, thin, 

 and light. At what dejitli ribbon tishes live is not known; jirobably the depths vary for 

 different species; but altliougii none have been yet obtained by means of the deep-sea 

 dredge, they nnist be abundant at the bottom of all oceans, as dead fishes or ft-agments of 

 them are frequently obtained. Some writers have supposed from the great length and 

 narrow shape of these fishes that they have been mistaken for 'sea serpents,' but as these 



