ON THE ANGUILLULIDyE, 93 



TABULAR LIST OF GENERA. 



I. LAND AND FRESHWATER. 



Spicules two, equal, with or without a single posterior median accessory piece. 



* Integument plain, or with longitudinal markings. Ventral excretory gland wanting. 

 \ Caudal sucker small. 



1. MoNHYSTERA. /w^Mmew^ with lateral cu'cular mark anteriorly. Oce/Zas single, often absent. Pha- 



ryngeal cavity none. (Esophagus cylindrical. Uterus unsymmetrical. 



2. Trilobus. Pharyngeal cavity cup-shaped ; no teeth. (Esophagus having three lobes at termination. 



Males with well-developed suckers in middle line above anal cleft. 



.3. MoNONCHUS. Pharyngeal cavity large, oval, having one upper tooth-Wke projection. Canal of 

 oesophagus indicated by three bright lines, 



tt Caudal sucker absent. 



4. Ironus. Pharyngeal cavity small, long, and narrow. (Esophageal canal bounded by three bright 



lines. 



5. Dorylaimus. Spear exsertile, at commencement of oesophagus, whose canal is indicated by three 



bright lines. Males having oblique integumental markings on posterior extremity, with or without 

 small median suckers above anal cleft. 



6. Anguillula. Pharyngeal cavity very small. (Esophagus having oval swelling at termination, con- 



taining a simple valvular apparatus. Uterus unsymmetrical. Spicules long and narrow. Acces- 

 sory piece single, distinct. 



** Integument with transverse stria. Ventral excretory gland present or absent. 

 t Caudal sucker present. 



7. Tripula. StricB well marked. Pharyngeal cavity none. (Esophagus with constricted portion at 



termination. Three large ^Jores through integument in anterior part of ventral region. 



8. Diplogaster. Stria transverse and longitudinal. Pharyngeal cavity cup-shaped, with small horny 



plates at bottom. (Esophagus having large muscular swelling at middle of length. Sucker very 

 minute. Accessory portion of penis well marked. 



^9. Plectus. Pharyngeal cavity long and narrow. (Esophagus having oval swelling at terminatioil, 

 provided with a complex valvular apparatus. Ventral gland having twisted duct opening near mid- 

 dle of oesophagus. Uterus symmetrical. 



''lO. Aphelenchus. Spear simple, at commencement of oesophagus, which terminates in a large 

 rounded muscular swelling. Ventral gland-opening posterior to termination of oesophagus. Uterus 

 unsymmetrical. Spicules simple, without accessory piece. 



* All the animals belonging to the genera having this mark affixed to them have a modification of the ventral 

 gland, and are endowed with a remarkable tenacity of life. 



