THE COAST OF CALIFORNIA. 7 



POLYORCHIS PENICILLATA A. Ag. 



(PLATE IV, B^IGS. 6, 7.) 



Many specimens of this Medusa, were found near the 

 wharves at Santa Barbara, Santa Cruz and San Francisco. 

 The jelly-fish is very conspicuous on account of the circles 

 of dark-purple tentacular bases and the extended wreath 

 of the tentacles. It is the most magniticent of all the west 

 coast HydromedusoB which were observed. 



The bell is lars^e, about one and one-half times as hiijh 

 as broad. It has a slightly yellow color and a small, 

 rounded apical prominence. The bell walls are thin and 

 of al)out uniform thickness throughout. 



Kadial tubes four. Each radial tube has lateral branches 

 which arise in pairs opposite each other. These lateral 

 branches often subdivide or become forked at their ends. 

 The largest subdivisions are situated about half the dis- 

 tance from the apex of the bell to its margin. The lower 

 extremities of the four radial tubes, at their junction with 

 the circular tubes, are ordinai'ily destitute of lateral ap- 

 pendages. The motion of the bell is sluggish, not unlike 

 that of Nemopsis. 



The length of the tentacles is greater than the altitude 

 of the bell, and these organs are ordinarily, when at rest, 

 carried at right angles to the bell walls. A. Agassiz found 

 in the specimen which he described, thirty-six tentacles, 

 or eight between each pair of tentacles which hang from the 

 neighborhood of the junction of the radial and marginal 

 canals. In the largest specimens which were taken at 

 Santa Barbara, there are more than thirty-six tentacles or 

 sixteen on a similar section of the bell rim. Counting all 

 the tentacular appendages in many specimens there are, 

 on an average, sixteen between each pair of radial tu1)es. 

 The four tentacles of the radial tubes and those from the 



