940 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



[14] 



preserved. The followiug description w as made from all the specimeiis. 

 No. 2 of the tables is figured in PI. lY, and No. 4 in PI. V. 



Specimens examined. 



These specimens will be known throughout my descriptions by the 

 Arabic numbers (1-8) prefixed to the catalogue number. 



The following table represents in tabular form the number of tenta- 

 cles, sense-bodies, marginal lappets, diameter of the central disk, and 

 width of the corona in each siiecimen. The diameter of the central disk, 

 me asured from the inner walls of the coronal ditch on each side, seems 

 to vary less from the action of the alcohol than the true diameter from 

 margin to margin. Tn smaller specimens it is extremely difficult to tell 

 from the abnormal position of the subumbral muscle the external limit of 

 the corona. The measurements, therefore, of the latter i)art (corona) are 

 not relatively so accurate as those of the central disk. From the nature 

 of the case, all measurements are probably too small for living repre- 

 sentatives. 



Umbrella flat, discoid, with a diameter six to eight times the vertical 

 thickness at the center. Umbrella is divided into two regions, a central 

 disk [dis. cent.) and a i^eripheral corona. The breadth of the corona is 

 about one-quarter the diameter of the central disk. The diameter of 

 the central disk varies in different specimens from 14 to 45"""; breadth 

 of the corona from 5 to 14""". Between the central disk and the corona 

 is a coronal furrow [fos. cor.). The inner border of the corona, which 

 forms the outer wall of the coronal ditch (furrow), is formed by a thin 

 yet strong muscle. There are from 22 to 28 tentacles, the same number 

 of sense-bodies and twice as many marginal lappets. 



