614 CAMBRIAN JELLY FISHES— WALCOTT. vol. xviii. 



}. 2. Esunibrella view of an imusually rotund specimen. A projecting interra- 

 dial lolie or arm is shown at x. 



2a. Subniubrella view of tig. 2. The interradial lobe or arm is shown at x, and 

 a broken subnmbrella lobe at h. The interradial lobe at a did not con- 

 nect with an exumbrella lobe. 



2h. Side view of 2 and 2a. What is considered to be an interradial lobe is 

 shown at a. 



3. An exumbrella iu which the interumbrella lobes are a prominent feature. 



The appearance is as though one medusa was resting upon and clasping 

 the one beneath. The exumbrella lobes {a to /), however, merge into 

 the subumbrella lobes, a to f of fig. 3a. 

 3a. Subumbrella view of tig. 3. 



4. View of a specimen worn hy erosion so as to show the radial canals of the 



exumbrella lobes. 



5. Transverse section, cut so as to show the radial canals of the six umbrella 



lobes and the central stomach of the umbrella disk. 



6. Side view of a specimen in which the subumbrella lobes are shown beneath 



the broader exumbrella lobes. 



BrookxeUd cotifiisa, 



FiciS. 7, 7a. Views of the exumbrella and several of the interradial lobes. The rela- 

 tions of the two sets of lobes aie shown bj^ the side view, fig. 7a. 

 7/). Subumbrella surface of fig. 7. The irregular arrangement of the lobes and 

 the oral aruis is well shown. 



Laotira camhria. 



Vm. 8. Transverse section of an irregularly lobed specimen, showing the aiTange- 

 meut of the exumbrella canals. 



Plate XXXII. 



Laofira caiitbria. 



Fid. 1. Subumbrella view of a small specimen with four lobes. 



2. ?2xnml)iella \ iew of a small specimen with six loltes. In both figures, 1 and 



2, the original form has been obscured by a deposit of silicious matter 

 about the lobes. 



3. A tyjiical illustration of the regular variety of the species. It has five prin- 



cipal exumbrella lobes and two small interradial lobes. 

 3a. SuT)umbrella view of fig. 3. The five subumbrella lobes are united at the 

 center, but not with the same regularity as in Brooksella aJiernnta. 

 (See Plate XXXI, fig. la.) 



4. Exumbrella view of an irregularly lobed specimen. 



4rt. Subumbrella view of fig. 4. The slight irregularitj' of arrangement of fig. 

 3rt has increased, aud two centers united by a transverse lobe are shown. 

 One of the oval arms is shown at x. 



5. Dorsal surface of an elongate specimen, iu which three centers are connected 



by lobes radiating from one to the other. 



6. A worn specimen iu which fission has proceeded so far as to lea\e but one 



lobe connecting what are otherwise two individual specimens.' 



' For fission in Medusa^, see Dr. Arnold Lang's memoir on Gaalrohlastd raffaeli. 



