JELLY-FISHES. 



Ill 



Four other curious appendages called auricles are found on the sides of the body- 

 in the grooves which lie on opposite ends of a horizontal diameter of the body, and 

 which are enclosed by the edges of the lateral lobes. These auricles are -simply exten- 

 sions of the body walls on the sides of the mouth, and their edges are skirted by vibra^ 

 tile plates somewhat like those found on the exterior of the body in the lines mentioned 

 above. 



The stomach and chyme tubes, vessels analogous to veins and arteries, in Bolina 

 do not differ greatly from the same structures in other Ctenophora, but are highly 

 characteristic as compared with similar bodies in other medusae. -The mouth of Bolina 

 is a narrow, elongated slit, opening with a correspondingly flattened receptacle called 

 a stomach. From the end of this stomach opposite the mouth, there arises a number 

 of vessels which pass to various regions of the body. One of the most important of 

 these is continued directly to the aboral pole of the medusa, and is known as the fun- 

 nel. Of the others, four, after a bifurcation, pass to the vicinity of the rows of combs, 

 and following a meridional course, eventually join each other in pairs near the oppo- 

 site pole of the jelly-fish from the sense-body or in the lateral lobes. There are two 

 tubes which originate from the base of the funnel and extend along the sides of the 

 body to the tentacles which from their characteristic course have always attracted 

 attention. Their function seems to be to convey the nourishing fluid to the tentacles 

 into which they eventually open. 



There are several genera of cteuophorous medusae allied to Bolina. One of the 

 most pompous of these, as well as the largest of the comb-bearing jelly-fishes, with 

 enlarged lateral lappets is a genus called Chiaja. This genus is remarkable in manj- 

 particulars, but more especially in the great length of the auricles which appear as 

 long, filament-like tentacles, and the very complicated course 

 of their chymiferous tubes. 



Many classifications have been made of the Ctenophora, but 

 as yet all are open to objections of some kind. One of the last 

 suggestions with this subject in view emphasizes the presence or 

 absence of the tentacles. By this classification we would have 

 the Ctenophora divided into the Tentaculata and the Nuda, 

 accordingly as tentacles exist or are wanting. In the genera 

 which we have already considered, with the exception of Ocyroe, 

 well-developed tentacles are found either in the larval or adult 

 condition. 



Probably the best example, however, which might be men- 

 tioned of a tentaculated ctenophore is the genus Cydippe or 

 Pleurobrachia. There are often in our New England bays and 

 harbors, after a southeasterly wind, a number — myriads at times 

 — - of little transparent gyrating spheres, not larger than a com- 

 mon marble. These little gelatinous spheres move through the 

 water with a great variety of motion, and seldom change in any 

 important particulars the regular spherical form of their bodies 

 in the mariner characteristic of the genera of Ctenophora to 

 which we have referred. When the cause of this variety in 

 motion is sought out, it will be found that on the surface of the body there are a num- 

 ber of iridescent lines extending from one pole to another, and that each of these lines 

 is formed of a number of minute comb-like bodies such as exist in other Ctenophora. 



Fig. 105. — Pleurobrachia 

 rhododactyla ; only a 

 portion of fclie ten- 

 tacles shown. 



