936 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



[10] 



Of the two new species here described, A. Bairdii more closely resem- 

 bles A. Wymllii than does A. Verrillii. They are easily distinguished 

 by the narrow and long socles of the sense- bodies in the latter, and the 

 greater prominence of the external coronal muscle as seen from the ex- 

 umbral side. It must be confessed that all these features may be the 

 result of alcoholic contraction, and it will be no surprise to me if live 

 specimens shall show that we have here only a single species. 



Atolla Bairdii, sp. nov. 



Specimens examined. 



Uxumhrella. — The central disk, discus centralis {dis. cent), is disk-like, 

 with the upper surface slightly rounded. The walls are translucent, so 

 that the api)endages to the lower floor can be indistinctly seen throu;ih 

 them. Color, slightly blue, with iron-red rust-colored patches, espe- 

 cially on the border of the coronal furrow. Twenty-two slight notches on 

 the periphery of the central disk, each notch corresponding with the 

 tentacular socle. Diameter of central disk, 53""" ; altitude, about 10""". 



The coronal furrow {fos. cor.), which separates the central disk from 

 the corona, has a reddish color in certain portions. Furrow deei>, broad 

 at bottom, slightly overarched by the wall of the central disk. 



The corona or peripheral region of the exumbrella is bounded axially 

 by the coronal furrow, and includes all that part of the umbrella on the 

 abaxial side of the coronal furrow. It is composed of four regions, whicli 

 are as follows, beginning with the most axially placed : 1. Undivided 

 zone, whose inner walls are the abaxial w^alls of the coronal furrow, and 

 whose outer bounding line is indicated superficially by a slight groove 

 of reddish color {m. cor.). This zone may be called the inner corona 

 {i. cor.). 2. A zone formed of twenty-two gelatinous blocks, placed side 

 by side, bearing the tentacles, and separated from each other by shallow 

 grooves also of reddish color. This is the zone of the tentacular socles 

 (sac. ta.). 3. A zone of twenty-two gelatinous blocks, non-continuous, 

 separated from each other by the tentacles. These blocks bear the mar- 

 ginal sense-bodies {mg. sh.), and are the socles of the rhopalia or sense- 

 bodies {soc. sb.). 4. A i)eripheral region of the corona made up of forty- 

 four marginal lappets, or patagia {mg. Ip.). 



1. The internal corona {i. cor.) is a narrow ring-shaped zone, undi- 

 vided, its inner wall forming the peripheral wall of the coronal furrow. 

 Its outer border is marked by the slight furrow (m. cor.) which separates 

 it on the peripheral region from the second zone, that of the tentacular 



