WITH NOTES ON THE WEST INDIAN SPECIES. 225 



The following tabulation may serve as a synopsis of the 



FAMILIES AND GENERA OF ENTEROPNEUSTA. 

 Family I. PTYCHODERIDAE, Spengel. 



Proboscis usually shorter than collar; coruua of nuchal skeleton do not extend 

 backwards beyond the middle of the collar ; dorsal unpaired roots unite the medullary 

 cord of the collar with the epidermis ; efferent vessels of proboscis united in one 

 transverse plane by a circular vessel with the ventral blood-vessel of the collar ; 

 peripharyngeal space containing circular muscles completely surrounds the wall of the 

 throat continuously up to the level of the buccal orifice ; perihaemal cavities do not 

 contain transverse muscles ; circular muscles outside the longitudinal muscles usually 

 present in body-wall of trunk ; genital pleurae well-developed or vestigial ; lateral 

 septa carrying the genital blood-vessels present ; external liver-saccules present (except 

 in Pt. ruficollis n. sp.). 



Genus. PTYCHODERA Eschscholtz, char, emend. Spengel. 

 With the characters of the family. 



A. Gill-slits opening freely and directly to the exterior. 



Subgenus i. Chlamydothorax, Spengel. 

 Genital pleurae with ventral origin. 

 Ex. Pt. flava Esch., Pt. erythraea Spengel, Pt. bahcumensis Spengel. 



B. Gill-slits opening into pouches which discharge to the exterior by dorsal gill- 

 pores. 



Subgenus ii. Tauroglossus, Spengel. 



Genital pleurae with dorsal origin. 



Ex. Pt. aperta Spengel, Pt. clavigera (Delle Chiaje), Pt. gigas (Fr. Muller), Pt. 

 aurantiaca (Girard), Pt. australiensis Hill, Pt. carnosa n. sp., Pt. biminiensis n. sp., Pt. 

 jamaicensis n. sp. 



Subgenus iii. Ptychodera, s. str., Spengel. 



Genital pleurae vestigial, reduced to ridges. 



Ex. Pt. minuta (Kow.), Pt, sarniensis (Koehler), Pt. hedleyi Hill, Pt. ruficollis n. sp. 



Family II. SPENGELIDAE, no v. fam. 



Proboscis longer than collar; stomochord produced anteriorly into a long vermi- 

 form process; cornua of nuchal skeleton extend to posterior region of collar; roots 

 absent or vestigial ; efferent vessels of proboscis pass obliquely downwards to posterior 

 end of collar to unite with the anterior end of the ventral vessel of the trunk ; 



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