126 THE VOYAGE OF H.M.S. CHALLENGER. 



periston! remain free from tentacles. Horizontal diameter of the umbrella, 120-160 mm. ; 

 vertical diameter, 30-40 mm. 



Habitat. — The Mediterranean. The following description and figure are taken from 

 four large, well-preserved spirit specimens which I owe to the kindness of my friend 

 Gregor Buccich at Lesina, and which he found on the coast of Dalmatia, near the island 

 of Lesina. A small fragment of a Medusa which I found in a bottle of the Challenger 

 collection appeared to be identical with these. This bottle (which also contained the 

 fragment of a Pectanthes asteroides, p. 20) was marked Station 4, entrance to the 

 Straits of Gibraltar. Lat. 36° 25' N., long. 139° 28' E. Depth, 600 fathoms. 16th January 

 1873. Further research must prove whether this remarkable Cyaneid (as yet the first 

 and only Cyaneid of the Mediterranean) be really a deep-sea Medusa or not. 



The umbrella (PI. XXX. fig. 1, PI. XXXI. fig. 8) forms a flat disk 12-16 cm. in 

 diameter and 3-4 cm. in height. The exumbrella is smooth, depressed on the whole, 

 and is divided by a shallow marginal coronal furrow into a thick central umbrella disk and 

 a thin peripheric corona of lobes (velarium). The radius of the former measures 55 mm., 

 that of the latter 25 mm. In the smooth upper surface of the central umbrella disk, 

 which is only slightly vaulted on the whole, we can distinguish sixteen dark radial 

 streaks which are simple in the inner third but cleft into two diverging limbs in the 

 middle third so as to form the same characteristic star figure as in Chrysaora (System, 

 taf. xxxi.). The peripheric corona of lobes (or velarium) which is more strongly vaulted 

 outwards, shows sixty-four deeper radial furrows, of which the one half appears as pro- 

 cesses of the thirty-two disk streaks, whilst the other half are placed between the streaks. 

 Besides these there are several (usually three) finer furrows visible between every second 

 of these sixty-four deep radial furrows in the exumbrella of the umbrella corona, so that 

 it appears thickly ribbed over its whole outer surface (fig. 8). The gelatinous substance 

 of the umbrella appears thick and firm, almost like cartilage. It is as much as a 

 centimetre in thickness in the central umbrella disk, decreases suddenly at the coronal 

 furrow, so that it is only one to two millimetres thick at the soft and very mobde 

 umbrella margin. 



The umbrella margin appears at first sight to be perfectly circular and only slightly 

 indented ; closer examination, however, shows that the whole umbrella corona (25 mm. 

 broad) is really composed of eighty long, narrow, marginal lobes, fused together by then- 

 edges, whose distal edges project a little at the umbrella margin as slight curves, 

 separated by shallow indentations (as in many Ehizostoma). Sixteen of these eighty 

 fused coronal lobes run out in pairs from the eight rhopalia, and may be regarded as 

 eight pairs of fused ocular lobes ; the other sixty-four were originally tentacular lobes, and 

 may also be termed velar lobes, as they have no longer any relation to the tentacles. 

 Eight velar lobes between two ocular lobes, or actually eight velar double lobes, as they 

 appear divided in two by a fine median furrow, therefore fall in each octant of the 



