96 PROCEEDINGS OF THE ACADEMY OF [1879. 



The characters of the family seem at present to be formidable 

 in the following way : 



Corpus subquadrilaterale, subelongatum. Velum frontale sat 

 magnum, integrum vel sub-bilobum, margine laciniis tentaculari- 

 bus fimbriatum. Rhinophoria vagina tubulosa, erecta, margine 

 revoluto retractilia ; petiolo cylindrico ; clavo culmine obtuso obli- 

 quo margine pennis bipinnatis instructo. Branchiae numerosae, 

 subpedicellatse, arbusculi-formes, insequales, margine palliali pro- 

 minulo serie simplici dispositse. Anus lateralis. 



Bulbus pharyngeus magnus. Mandibulse fortes, plus minusve 

 elongatse, sat applanatse. Radula lata, multiseriata. Series den- 

 tium multidentatae, dens medianus latns, depressi\s vel nonni- 

 hil elongatus, subpyramidalis ; utrinque dens lateralis mediano 

 subsimilis, sed magis elongatus ; dentes exteriores hamiformes, 

 margine Isevi vel denticulate 



Heparnon ramificatum. Sperraatotheca unica. Penis elongatus, 

 inermis. 



The body of the' Tr it 'oniidas is rather stout and strong, some- 

 what elongated, subquadrilateral. A large frontal veil covers the 

 head ; it is simple or more or less bilobed, the margin with more 

 or less numerous, rather short, digitations. The sheaths of the 

 rhinophoria erect, tubulous, with revoluted margin; their stalks 

 cjdindrical, the club oblique above, with bipinnate plumes on the 

 margin. The gills are rather numerous, unequal, subpetiolate 

 arborescent, inserted one behind the other upon the somewhat 

 prominent pallial margin. The anus is before the middle of the 

 right side, the bulbus j)haryngeus very large and strong. The 

 mandibles are very strong, elongated, the anterior extremity (arti- 

 culation) arched upwards. The interior cutting edge coarsely 

 serrated. The radula broad, with many series of plates, the series 

 with many plates. The rhachidian tooth broad or more elongate 

 subpyramidal ; with a somewhat similar, but more elongated, 

 lateral on each side. The remaining laterals (uncini) hook-shaped, 

 the hook with smooth or denticulated margin. The liver is as in 

 the Dorididae, quite without ramifications. As in the former 

 groups a single spermatotheca (the spermato-cysts 1 wanting). 

 The penis elongate, somewhat flagelliform, unarmed. 



The Tritoniidas form a connecting link between the large group 



1 I have used this name for the secondary spermatotheca of the Dorididm. 



