66 VERMES. 



has suggested, the branchial sac of the Ascidian is (as are the en- 

 dostyle, tentacular filaments, &c.) a new and distinct development, 

 then they have no homological representations in the Polyzoa. 



Kecently Kay Lankester places this class with Brachiopoda 

 and Lamellibranchiata to form his Lipocephala ; Huxley asso- 

 ciates the Polyzoa with the Brachiopoda as " a division apart," 

 for which he proposes the term " Malacoscolices." Brooks main- 

 tains that the union of the Brachiopoda and Polyzoa is "without 

 scientific value." Lastly, Schmarda (1878) keeps the old name 

 " Molluscoidea " for this class and Tunicata. 



Cyphonautes is a remarkable form not yet determined ; it has 

 been said to be the larva of Memf)ranipora. 



Schmarda gives 600 living and 1800 fossil species for this 

 class. 



Mouth without an epistome GYMNOL^EMATA. 



Mouth with an epistome PIIYLACTOL.EMATA. 



Order I. GYMNOL^MATA. 



STELMATOPODA. INFUNDIBULATA. ECTOPROCTA. 



Separation of individuals complete. No epistome. Lopho- 

 phore circular. 



This order is composed of marine organisms, often taken for 

 seaweeds, and having a close resemblance to the Calyptoblastea ; 

 the former, however, differ in that the cells do not communicate 

 except by the external investing cuticle [ectocyst]. In one of the 

 suborders [Chilostomata] this cuticle gives rise to certain ap- 

 pendages called " avicularia," "vibracula," and " ooecia," or 

 " oocysts." The avicularia are organs of prehension, consisting 

 of a movable portion or mandible and a corresponding fixed 

 portion ; the vibracula consist of a cup having a movable seta 

 attached to it ; the ooecia or oocysts are globular cells receiving 

 the ova. 



The sequence of the families in the following list is after Busk ; 

 a later arrangement by Glaus omits many of the families and 

 genera of the former, while, on the other hand, the latter gives two 

 or three families not noticed by Busk. 



There are three suborders : 



Mouth of the cells with a movable lip CHILOSTOMATA. 



Mouth of the cells without a lip. 



Mouth round, open, not setose CYCLOSTOMATA. 



Mouth setose CTENOSTOMATA. 



