THE MEDUS.E. 173 



due to shrinkage. The velum is very broad, about 2 to 2*5 mm. in width. The stomach 

 is cylindrical in shape when stretched out, and is about half the length of the umbrella- 

 cavity. The mouth has four small lips. The gonads are upon the eight radial canals, 

 and occupy, as a rule, the central third portion of the canals, but they vary slightly in 

 position, being in some specimens a little nearer the stomach, in others a little nearer 

 the margin of the umbrella. The gonads are at first linear, but when mature they 

 become cylindrical. Their length is variable, about 1 to 3 mm. There are eight per- 

 canal tentacles, 8 inter-canal cirri, and IG ad-canal cirri ; 16 sense-organs (two in each 

 octant, one next the inter-canal cirrus and one next the per-canal tentacle), but perhaps 

 more. 



Size : Umbrella up to 10 mm. in width and 7 mm. in height. (Most of the specimens 

 about 6 to 8 mm. in width.) 



Early Stages : There are a few early stages. One of these measures 2 mm. in diameter. 

 It has 8 per-canal tentacles, 8 inter-canal cirri, and a sense-organ next to the inter-canal 

 cirrus. No gonads visible. 



Sense-organs. — The search for sense-organs with a moderate high-power lens has not 

 yielded very definite results. When sense-organs could be found I usually saw the 

 one next to the inter-canal cirrus. In three specimens I clearly saw a sense-organ 

 next to the per-canal tentacle, and a few other specimens also showed a cell which some- 

 what resembled a sense-organ in a similar position. In one specimen, and in one octant 

 only, I saw three sense-organs ; as it only occurred once, it may be an instance of 

 numerical variation. It may, however, be simply normal developmeat, in which case 

 the species would probably have four sense-organs in each octant. The sense-organ 

 next the inter-canal cirrus appears, from its size and frequency in the specimens, to 

 develop first, and then next in order comes the one near the per-canal tentacle. The 

 latter is usually very small in size and very hard to see. 



Occurrences : Surface. 23 b (1 specimen). 



25 to fathoms. 30 h (3), 31 a (1). 

 50 to fathoms. 21^ (1), Tog (1), 25 k (5), 26 n (2), 30 d (1), 30 I (3), 



31 i (4), 36d(l). 



75 to fathoms. 32 m (2), 35 a (1), 35 c (1), 36 « (1). 

 100 to fathoms. 21 b (5), 21 c^ (4), 21 e (2), 25 d (2), 30 h (1), 32 d (4), 



32 i (2), 32 m' (1), 2,2 2i (1), 33 f/ (4), 31 ^* (1), 

 34 d (2), 35 b (2), 35 (/ (4), 35 x (2), 36 h (2). 



200 to fathoms. 36/7(1). 

 250 to 5 fathoms. 36/i(l). 

 350 to fathoms. 36 I (1). 



This species was evidently occupying a zone between 50 and 100 fathoms, and there is 

 no proof that it occurred at a greater depth. 



Distribution. — Canary Islands. 



The identification of the species belonging to the genus Tlhopcdoiiema appears to me to 

 be becoming rather difficult. I do not think that I shall be going far astray in assigning 



