472 ON THE FAUNA AND BOTTOM-DEPOSITS KEAR THE 30-FM. LINE 



from the pure sand and from the pure mud. Chadwick (No. 15) records the species in 

 great numbers off the southern shores of the Isle of Man in 10 20 fathoms on a bottom 

 chiefly of nuUipore and gravel. 



Although these records are somewhat uncertain, owing to the difficulty of interjireting 

 the exact meanings attached by the authors to the terms employed, they appear on the 

 whole to indicate that when the species is found in very large numbers the bottom-deposit 

 is a mixture of coarse gravel or sand with mud, similar to that upon which it is abundant 

 in the neighbourhood of the Eddystone. 



Echinus esculentus (Chart V.). Although present on most of the 

 coarser grounds this species was nowhere very numerous, being repre- 

 sented by one or two specimens in a haul of the dredge and five or six 

 in a haul of the otter-trawl. It was taken on all the gravel and shell 

 grounds lying to the westward of the Eddystone, on Grounds IV. and 

 XIII. to the eastward, and on the Bolt Head and Prawle Grounds. It 

 is absent from all the fine sand grounds. 



Habits. This is a wandering species, able to travel best upon hard ground. It is 

 gregarious, large numbers being often found together. Its food is very various, and 

 in confinement it will devour almost any dead animal matter. Specimens from moderate 

 depths have the intestine filled with fine sand and silt, which is so common a form of food 

 for Echinoderms. Professor MacBride informs me that in the estuary of the Clyde he has 

 found the species on the shore, and that it there feeds upon red and brown sea- weeds.* In 

 the Plymouth district it always occurs, so far as I am aware, at de])ths greater than 18 or 20 

 fathoms, where such sea-weeds do not grow. It is probable that the difference of distribu- 

 tion in the two districts is due to the very much greater effect of wave action in the neigh- 

 bourhood of Plymouth than in the sheltered waters of the Clyde. Petersen (No. 95) 

 found in the stomach of one sjiecimen remains of Annelids, Barnacles, Polyzoa, Echinus 

 spines, Ostracods, Algae and Hydroids, together with sand. 



Di.sTRiBTJTioN. Geographical. Eastern side of North Atlantic, North Sea, Mediter- 

 ranean, Port Natal, and John Adam's Bank (Brazil) {fide Bell, No. 7). 



Dqith. From shore (Forbes) to 110 fathoms (Bell). 



Bottom-deposit. Mbbius and Biitschli (No. 88) record Echinus esculentus from stony and 

 rocky ground (5-30 fathoms). ]\Ieissner and Collin (No. 76) give one record only, from 

 a coarse bottom {Riffcjrund). Petersen obtained it from rocky ground and from sand and 

 nuid. Chadwick (No. 15) records it from between tide-marks. 



Echinus acutns (Chart V.). Like E. esculentus this species was never 

 numerous, and its distribution coincided closely with that of the allied 

 form. On the following grounds, however, upon which E. esculentus was 

 taken, no specimens of E. acutus were obtained, viz., XVI., XII., XIII., 

 and XVIII. On Ground VII. only one specimen was taken, in haul 54, 

 and it was also represented in one haul only (34), on Ground IV. On 

 Ground XVII. several specimens were obtained in haul GO. It was 

 entirely absent from the sand. On the whole the species was most 

 numerous on deposits made up of a mixture of gravel and muddy sand. 



Dlstkicution. Gcoyraphiad. Atlantic from Norway and Halifax to Ascension, North 

 Sea, Mediterranean, off Kermadec Island (fide Agassiz, No. 1, and Bell, No. 7). 



Depth. To 1350 fathoms [Agassiz]. There is no evidence tliat the species is ever found 

 between tide-marks. From Koehler's records {Caudan, No. 61) it is clear that this is one 

 of the commonest Echinoids at depths of from 80 to 400 fathoms in the I'.ay of Biscay. 



* Compare M'Intosh, Murine Invertebrates and Fishes of St. Andrcios, p. 95. 



