102 TELEOSTEI : ACANTHOPTERI. — XX. 



DISCOCEPIIALI. — Of these various suborders, we notice first 

 tlir Discocephali, a small group characterized by a singular modi- 

 fication of the dorsal fin. 



Family L. ECHBNEIDID^B. (The Remoras.) 



Body fusiform, elongate, with minute smooth scales ; mouth wide, 

 with villiform teeth ; lower jaw projecting. Spinous dorsal changed 

 into a sucking disk placed on top of head and composed of a double 

 series of transverse movable cartilaginous plates. Opercles un- 

 armed, P. placed high. V. I, 5. D. and A. long, similar ; gill- 

 rakers short ; no pseudobranchia; ; no air-bladder. Vertebra? more 

 than 24. Genera 3, species 10. Of the open seas, attaching them- 

 selves to sharks, sword-fishes, tunnies, and floating objects, and thus 

 carried for great distances in the sea. The relationships of this 

 group are still uncertain. Their resemblance to Elacate is such that 

 they apparently should not be placed very far away from the next 

 family. 



a. Body slender; vertebrae 14 + 16 = 30; disk of 21 to 25 lamina? ; not more 



than J body Echeneis, 117. 



aa. Body robust; vertebras 12 + 15 = 27; disk more than J body, of 16 to 18 

 laminae. 



b. Pectoral rays normal, soft Remora, 118. 



bb. Pectoral rays stiff, broad, ossified Rhombochirus, 119. 



117. ECHENEIS (Artedi) Linnanis. {lytvr]U, an ancient name 



meaning one who holds ships back.) 



254. E. naucrates L. Sucking-fish. Pegador. Blackish, 

 belly dark; a black lateral stripe; corners of C. pale. Head 5^; 

 disk 3-f. shorter than D. ; width between P. 1\. D. XXI to XXV- 

 32 to 41. A. 32 to 38. L. 30. Warm seas. X. to Cape Cod; 

 the commonest species, on sharks, etc. (Eu.~). (yavKparris, pilot.) 



118. REMORA Gill. (Ancient name, meaning one who holds 



back.) 



a. Dorsal about XVIII -23. (Remora.) 



255. R. remora (L.). Remora. Sucking-fish. Uniform 

 dusky : head 4 ; disk 2f, longer than D. ; width between P. 5^. A. 

 25. L. 12. Warm seas, N. to N. Y. (Eu.) 



aa. Dorsal about XVI - 30. (Remoropsis Gill.) 



256. R. brachyptera (Lowe). Sword-fish Remora. Light 

 brown. Head 4; disk shorter than dorsal; width between P. 6-J-. 

 A. 26. Warm seas, rarely N. ; on sword-fish, (fipaxvs, short; 

 irrepov. fin.) 



119. RHOMBOCHIRUS Gill. (po>/3os, rhomb; x dp, hand.) 



257. R. osteochir (Cuvier). Spear-fish Remora. Light 

 brown: mouth small; disk very large. Head 5; disk 2J; width 



