60 BULLETIN OF THE 



Nitsche ('71, pp. 431, 432) our first intimate knowledge of this organ. 

 He believed it to consist in the adult of Flustra of a single cell layer, 

 in which are imbedded (or applied?) longitudinal and circular muscle 

 fibres. He believed the kaniptoderm to be formed gemmigenetically only 

 by the outer cell layer, the derivative of the mesoderm. Repiachoff'('75, 

 pp. 138, 139) observed in Tendra (Membranipora) *' die Doppelschichtig- 

 keit der Tentakelscheide nicht nur bei den jungen Knospe sondern audi 

 bei den ganz ausgewachseneu, ofi'enbar schon langst functionirenden, in 

 ihrem mittleren Theile ganz braunen ' Polypiden,' " and later ('76, p. 152) 

 a similar two-layered condition of the kamptoderm (Tentakelscheide) 

 in Membranipora and Lepralia. Ehlers ('76, p. 37) finds a single layer of 

 cells in the kamptoderm of the adult Hypophorella (Ctenostome), which 

 he believes is continuous with the endocyst of the body wall, and thus 

 is ectodermal. He finds neither longitudinal nor circular muscle fibres. 

 Haddon ('83, p. 517) believes the kamptoderm to be derived from both 

 the inner and outer layer of the polypide bud. Vigelius ('84, pp. 33, 82) 

 describes it as arising from the mesoderm only (Parenchymegewebe), and 

 as being essentially one-layered, both longitudinal and circular muscles 

 lying in this layer. Barrois ('86, p. 74) derives the kamptoderm fi'om 

 the mesodermal layer only. Ostroumoff" ('86", p. 15) believes the kamp- 

 toderm to be two-layered and provided with muscles ; it is in his opinion 

 derived from both layers of the bud. Freese ('88, pp. 18, 19) studied 

 only the adult of Membranipora. He admits the presence of muscle 

 fibres, but believes the kamptoderm one-layered. Pergens ('89, p. 507) 

 states only that in the Cheilostomes studied by him the tissue of the 

 kamptoderm is composed "aus abgeplatteten Zellen, zwischen welchen 

 Langs- und Ringmuskelfasern eingebettet sind." Prouho ('90, p. 451) 

 states that in the primary polypide of Fhistrella this organ is early 

 differentiated, " et les deux couches de rudiment prennent part a sa for- 

 mation." Finally, Seeliger ('90, p. 587) : " Es kann danach keinem 

 Zweifel unterliegen, dass die Tentakelscheide ektodermalen Ursprungs 

 ist. . . . Das Mesoderm erscheint auf alien gelungeuen Schnitten von 

 der Tentakelscheide scharf abgesetzt." 



It is my belief that throughout the group of marine Gymnolsemata, as 

 in Paludicella and Phylactolaemata, the kamptoderm is derived from both 

 of the two layers of the polypide bud, is provided with a strong system 

 of longitudinal and a slight one of circular muscles, and contains in the 

 adult two layers, or at least modified representatives of two layers. I 

 have arrived at this conclusion from a careful study by sections of the 

 following genera : Bugula, Lepralia, Escharella, Flustrella, Bowerbankia, 



