130 BULLETIN OF THE 



the opposite end from its original junction. In the structure formed by 

 these changes we have the fully-grown condition of the complicated knob 

 of this Jelly-fish. (PI. I. fig. 7.) 



The resemblance of certain of the earlier stages in the growth of this 

 organ, or individual if one so designates it, to the adult in a different 

 genus is very great. Athoryhia has a tentacular knob with many points 

 of resemblance to the undeveloped forms which have just been described. 

 The figures of the knob of this genus, as given by Gegenbaur, Kolliker, 

 and Huxley, show a close likeness to the younger stages of the knob in 

 Physophora. 



While emphasizing this asymmetrical growth of the knob of the 

 young Physopliora, and suggesting a likeness to the same structure in 

 the genus Athoryhia, I recall the figures of the knob in the younger 

 stages of an Agalma, called by Leuckart Agalma clavatum. As Glaus 

 suggests, this species is probably the young of Agalma Sarsii. Leuck- 

 art's figures of ^. clavatum show a knob which assumes a similar asym- 

 metrical shape to that which exists in the knob of Athoryhia. This 

 naturalist* has already made the comparison of a tentacular knob of 

 A. clavatum with the same structure in Athoryhia. The comparison 

 seems to me a good one, and does not prevent a comparison of both 

 to the undeveloped tentacular knob of Physophora hydrostatica. A like- 

 ness is further indicated by the existence in each genus of terminal fila- 

 ments on the sacculus, provisional to be sure in Physophora, but none 

 the less definitely pointing out the relation of the structures under con- 

 sideratiomt 



II. The Mantle-Tubes of Apolemia uvaria and Gleba hippopus. 



A wish to find out the homology of the somatocyst of the Calyco- 

 phores led me to a study of the chymiferous tubes of the swimming-bells 

 throughout the tubular Jelly-fishes. Especially in Apolemia and Gleha, 

 from their aberrant forms, I hoped to find some facts bearing on the solu- 

 tion of this question ; and when I came to see the former of these genera 

 for the first time, my thoughts were turned to the question of its mantle- 

 tubes. This genus, in many respects allied to the Calycophoridse, is a true 

 Physophorid; yet, in the published description of its nectocalyces, I find 

 no mention of any structure which, I think, can be truly known as the 



* Siphon ophoren von Nizza, PI. XI IL Fig. 5, p. 91. 



t I find these structures in hydrostatica more leaf-like than they are represented in 

 Keferstein and Ehlers's plate of Physophora Philijjpi. 



