732 Proceedings of the Royal Irish Academy. 



Naecomedus^. 



Solmaris corona (Keferstein and EUers). 



JEgineta corona, Keferstein und Ehlers, 1861, p. 94, Taf.xiv., figs. 7-9. 



Solmaris corona, Haeckel, 1879, p. 358. 



In 1895, ttiree specimens were taken in July by the Misses 

 Delap. 



In 1896, only a solitary specimen in a damaged condition 

 was taken on July l7tli. 



In 1897, it first appeared in July, and disappeared in !N"ovem- 

 ber ; very abundant from July to the middle of September. 



In 1898, it first appeared in July and disappeared in Novem- 

 ber ; abundant during July and September. 



Altbougb tbe Valencia specimens do not agree in every detail 

 with the description given of Solmaris corona, yet the resem- 

 blance is so close that I do not feel justified in adding a new 

 species to the genus. 



The specific characters are mainly based upon the number of 

 sense-organs upon each lobe on the margin of the umbrella; 

 upon the shape of the lobe ; and upon the number of tentacles. 

 All of these organs increase in number with the growth of the 

 Medusa. 



The following are the principal characters of S. corona taken 

 from Haeckel's monograph : — 



Umbrella thi'ee to four- times as broad as high (14 mm. 

 broad, 4 mm. high). 27-30 lobes on the margin of the um- 

 brella ; nearly rectangular, twice as long as broad. Genital 

 band, simple, smooth ; in the outer half of the lower wall of 

 the stomach. 27-30 tentacles, twice as long as the diameter 

 of the umbrella. 60-80 sense organs (2-3 on each lobe). 



The specimens sent to me were difficult to woi-k upon, owing 

 to the contraction and cuiding up of the lobes of the umbrella 

 and the disappearance of most of the sense-organs in the for- 

 malin ; but some diagrams and sketches, made by the Misses 

 Delap from living specimens, helped me considerably in the 

 determination of the species. 



In taking the diameter of the tmibrella as a guide to the age 

 of the specimens, the following table shows that an increase in 

 the number of lobes, tentacles, and sense-orgaas takes place 

 along with the growth of the Medusa : — 



