CORONATA. 21 



versed. Another recent advance in our knowledge of the order has been the 

 demonstration by Maas (: 03) that in Linerges, as in Nausithoe, the two 

 canals which enter each marginal lappet unite, thus forming a continuous 

 festoon canal, instead of ending blindly, as early students of the genus 

 supposed. This discovery, already made by Vanhoffen (: 02^") and since 

 substantiated by myself on excellent specimens of L. mercurins from the West 

 Indies and of L. aquila from the Fiji Islands, brings the vascular system of 

 Linerges into fundamental agreement with that of all other genera belonging 

 to the order. 



Under the Coronata we may distinguish the following families: — 



Periphyllidae, with four sense organs. Under this family are two 

 sub-families : — 



a. Periphyllinae, with the ordinary radial arrangement. 



b. Paraphyllininae, with the radial arrangement of the marginal 



organs reversed. 

 Atorellidae, with six sense organs. 

 Ephyropsidae, with eight sense organs. 



a. Nausithoinae, lappet-canals simple, without subumbrellar sacs. 



b. Linerginae, lappet-canals branched, with subumbrellar sacs. 

 Atollidae,' with more than eight sense organs, and with an irregular 



number of metameres. 

 Recently Kassianow (: 01) has proposed another classification of this 

 group, based on unfamiliar, even if not wholly novel, grounds, which dif- 

 fers so essentially from the one outlined above that I cannot pass it by 

 without brief notice, even though Maas (: 07) has already reviewed it in 

 detail. Kassianow gives to the condition of the marginal lappets a much 

 higher importance than other students of the group have usually attached to 

 them, and he believes that in the homologies of these structures he finds 

 reason to discard the otherwise homogeneous order Coronata. According to 

 his view the rhopalar lappets of Periphylla and the eight lappets of Pericolpa 

 are not homologous ; nor are the eight adradial lappets of the latter the 

 true rhopalar lappets of that form. On the contrary, following Clans ('86), 

 he believes that he can find evidence in Haeckel's ('80) figures of Pericolpa 

 of the existence at the base of each of the four sense organs of a small, 

 undivided lappet. According to his theory these masked, and but slightly 



^ The name Collaspidae has usually been employed for this family, but since the genus CoUaspis 

 has been shown by Fewkes to be a syuonym of Atolla I follow the International rules of zoological 

 nomenclature in substituting Atollidae. 



