DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 315 



II. Caudal not fully ilifferciitiated, and often confluent. 



A. Veutial.s inserted on isthmus, not far from humeral symphysis BYTHITIN.E 



1. Pectorals simple. Eyes present. 



a. Lateral line present posteriorly, but broken in middle. 



i. Palatines dentigerous. Veutrals a pair of lilaments, each of two closely united rays. 



Bythites 

 ii. Palatines toothless. Ventrals a pair of simple rays Gkammonus 



b. Lateral lino obsolete posteriorly. 



i. Ventrals a pair of simple rays. 



* Lateral line distinct on front of body. 



t Palatines with teeth. Preoperculum unarmed. 



A. lle.ad scaly (except snout). Lateral lim^ indistinct. 



1. Operculum with a single spine. Vent median Cat,ETYX 



B. Head naked. Lateral line on trunk only. 



1. Operculum without a spine. Vent postmediaii Saccogastek 



2, Operculum with two spiues. Veutpremediau .. .. Uii'l.\c.\>ithopoma 

 ft Palatines with teeth. Preoperculum strongly armed. 



a. Head partially naked. Lateral lino obsolete ])osteriorly. 



1. Operculum with one spine, preoperculum with 3-4 Dicromita 



** Lateral line obsolescent, almost or quite invisible, 

 t A feeble spine on the operculum. 



A. Head smooth. Eyes small Bassozetus 



11. Head crested. Eyes large Glyptophidium 



1 1 Acute spiues on head-boues and opercles. 



a. a long, tapering tail. No pyloric ca;ca Dermatorus 



ii. Ventrals a pair of l)ilid rays. 



* Caudal rays exserted, but confluent with tlio.se of anal and caudal. 



t Head seal}'. 



A. Preoperculum with small spiues at its angle. 



1. Operculum with one ,si)ine Neobythites 



n. Preoperculum unarmed. 



1. Two spines on operculum. Ventrals close together. Bentiioco.metes 



2. One strong spine on operculum. Veutrals far apart Bassogigas 



C. Preoperculum with crenulated limb. 



1. Ventrals feeble, close together AxcocKl a 



tt Head naked. 



A. Lateral line not distinguishable. 



1. Several strong spiues ou head Celem.a 



u. Lateral line represented by a few large scales near shoulders. 



1. Head smooth. Tail very attenuate Mcebia 



** Caiulal not confluent with vertical fins, but without distinct peduncle. 

 t Teeth on .jaws, vomer and palatines in villiform bauds. 

 A. Preoperculum unarmed. Head scaled. 



1. A flat opercular spine. 



a. Snout much produced and dilated. Lateral line very indistinct 

 (or absent?) Barathkodemus 



2. Operculum with a bony ridge above, ending in a blunt point. 



a. Snout not produced, broad, rounded, flattened at tip. Lateral 

 liue obsolete posteriorly Pycxocraspedum 



3. Operculum a triangular flap, uiianued. 



a. Lower pectoral rays prolonged, the lowest filamentous. 



Nematonus 

 c. Lateral lino represented by three rows of pores, dorsal, lateral, and ventral, 

 i. Head spiuigerous. 



* Ventrals each of two distinct rays. Opercular spine moderate, straight. Porogadus 

 ** Ventrals each of two united rays. Opercular spine strong, curved Penopus 



2. Pectorals simple. Eyes absent or rudimentary. 



a. Body scaly. Eyes absent. 



i. Ventrals Idtid filaments. Teeth on jaw.s, vomer, and palatines Tauredophidicm 



3. Pectorals with lower rays ditterentiated. 



rt. Preopercidum armed with three spines, operculum with one. Lateral line obsolete pos- 

 teriorly. 



i. Veutrals simiile, not close together Pteroidonus 



ii. Ventrals bifid, ai)i)roximate Dicrolene 



