FROM THE EDDYSTONE GROUNDS TO START POINT. 471 



sand and shells, and tlie sjH-cies was associated with large nunihers of Ophiopholis acidcata 

 and Ophiolhrix fnujilis. Herdnian (No. 40, vol. viii., i)p. 17 and 20) records it in the 

 Irish Sea, once from shell sand and small gravel and twice from stony ground. In the 

 summer of 1896 I obtained this species in exceptionally large numbers off the mouth of 

 Fowey Harbour, a number of large stones being dredged at the same time. 



Ophiothrio: fragilis. The distribution of this species on the grounds 

 investigated is shown on Chart VIII. It occurs in by far the greatest 

 numbers on the coarse gravel grounds north-west and west of the 

 Eddystone. 'It has already been pointed out in the description of 

 Ground X. that 0. fragilis occurs upon it in very large numbers, so 

 much so that in some hauls {e.g., 89 and 95) the dredge came up half 

 full of specimens of the species, to the almost entire exclusion of any 

 other form. The species is also very abundant on the mixed gravel and 

 fine sand deposits to the north-west and west of this ground (IX., XL, 

 XII.), as well as on the finer gravel between the latter grounds and 

 the Eddystone (XIV.). It is also abundant on the mixed gravel and 

 mud (XIII.) south-east of the Eddystone, a ground the fauna of which 

 in many ways resembles that of the typical coarse gravel of Ground IX. 

 On the fine sand grounds, on the other hand (I., II., III., etc.), Ophiothrix 

 fragilis is very scarce, being generally only represented by a few small 

 specimens, which cling about the roots of Cellaria or hydroids. 



Habits. This is a creeping species which does not burrow. On the shore at low-water 

 it is often found hidden under stones, and it is often seen clinging to stones, shells, 

 and other solid objects brought up with the dredge. On those grounds where the species 

 is found crowded together in large numbers, such as Ground X., the stomachs of the 

 specimens examined have always been found to be filled with fine mud or silt, which, 

 as explained on page 380, is full of organic matter of various kinds. In shallower water the 

 species has been observed to feed on compound ascidiaus and other similar organisms. On 

 an old bottle recently dredged in the CattcAvater, covered with a compound ascidian 

 [Didemnid), there were a number of specimens of 0. fragilis obviously feeding upon the 

 ascidian. I do not think that actively moving animals, such as Polychaetes and Crustaceans, 

 upon which Ojhiv.ra feeds (see above, pp. 468 and 469), are captured by 0. fragilis. 



Petersen (No. 95) found in stomachs of this species Diatoms, Peridinidac, Polychaete 

 setae, vegetable cells, etc., together with fine sand grains, which evidently means that they 

 were feeding on the fine silt, as they do in this neighbourhood. The Polychaete setae 

 would probably be from the faeces of some other animal. 



Distribution. Geographical. Norway to Mediterranean (Mobius and Butschli, Lyman, 

 Bell). 



Depth. Bell (No. 7) records a specimen from 767 fathoms and Hoyle (No. 50) one from 

 516 fathoms. Hence the species, according to our present knowledge, has a somewhat wide 

 range, viz., from the .shore to 767 fathoms. It nmst, however, be noted that Ijoth Bell and 

 Hoyle mention the difliculty of distinguishing this species from the deep-water form 

 0. Luelkini, Wyv. Thoms. 



Bottom-deposit. Forbes (No. 22) mentions Ophiothrix fragilis as being fond of rocky 

 places, but rare in sandy localities. Mubius and Butschli (No. 88) found it on stony 

 ground in the fjords of Norway, on sand and gravel, and on muddy sand in the North 

 Sea. Meissncr and Collin (No. 76) found it very plentiful on mud and sand, on mud, and 

 on fine sand with sandy mud and stones. (The last ground would jjiobably Itc similar to 

 the Eddystone (iround X , on which the .species is so iilcntil'iil.) In tlie Kattegat IV'tersen 

 (No. 95) found fragilis chielly on the mixed sand and nuul. It was practically absent 



