THE EADIATINCt ORGANS OF THE DEEP SEA FISHES. 203 



/. murrai/i, and has examined and carefully described their minute struc- 

 ture. In the material of /. cKjamzil at my disposal these discs are not sutfi- 

 ciently well preserved to allow of their minute structure being studied. 

 All I can say is that I have seen nothing in them that would justify one in 

 supposing that they differed in any way from the organs described by 

 Moseley in /. iiiurm/ji. The hexagonal cylinder cells of the discs of /. 

 agassidi are about 20 /x long and 5 /a thick. 



(3) THE PISHES WITH TUBULAR RADIATING ORGANS. 

 MalthopsiS SpinulOSa Oarm.-in. 



Plate 1, Figa. 1, 3, Plate 3, FiRs B-i). 



This species has been described by Garman ("(ID, p. 106, Plates 21, 24). It is 

 (Plate 1, Figs. 1, 2) a flat (isli of horseshoe-shape with a stout conic tail. 

 The organ here to be described which may have a radiating function is 

 a medial tentacular papilla on tlie forehead just above the mouth (Plate 2, 

 Fig. 6 te). Garman ('9'.), p. lOG) states that this papilla is contractile and 

 can be extended and retracted at the will of the fish. In the state observed 

 by me it is about 6 mm. long and 1.5 mm. thick. This papilla is situated in 

 a depression so that it protrudes when retracted only .slightly beyond the 

 general surface of the fish. The apex of the papilla is divided into three 

 lobes, an upper somewhat leaf-.shaped one and a pair of lower massive 

 ones. 



The trilobed terminal part of the tentacular papilla of the only specimen 

 of Malthopds spiimJosa at u\y disposal was cut into a series of transverse 

 sections. These (Plate 2, Figs. 7, 9) show that its trilobed distal part is 

 supported by four stout longitudinal rods of semicartilaginons ti.ssue (Figs. 

 8, 9 s). The two lower ones are separate, the two upper ones joined to 

 form a band-shaped structure. These rods iire enclosed in shenths of con- 

 nective tissue from which septa (Figs. 7, 8, 9 c) radiate, chieily into the 

 massive ventral lobes, the interior of which is divided by them into a 

 number of longitudinal compartments. In the middle of the ventral surface 

 connecting the two ventral lol:)es a conspicuous hmgitudinal ridge is ob- 

 served, the interior of which is occupied by a pair of longitudinal muscles, 

 lying clo.se together (Figs. 8, 9 m). These are. no doubt, the mu.scles which 

 retract the tentacular papilla, while its extension is piobably brought about 



