336 GENERAL SUMMARY TO 



and formed of large multipolar cells and nucleated protoplasmic threads, intercom- 

 municating so as to form a network. No connection with the neighbouring epithelial 

 cells has been discovered ; though it seems very probable the connection exists." 



I have said enough to show how great has been our advance in knowledge with 

 respect to the animal of the Brachiopoda during the present century, or rather within 

 the last forty years. Much, however, has still to be made clear before the subject will 

 have been exhausted. 



Habitats and Bang es in Depth. — As is well known, Brachiopoda are inhabitants of the 

 sea ; and very much correct and valuable information concerning their habitats has been 

 obtained during the last fifteen years, and especially so with respect to their bathymetrical 

 and geographical distribution. Many important dredging-reports have been issued from 

 time to time, and we cannot proceed without especially alluding to a report on the Mol- 

 lusca and Radiata of the ^Egean Sea by that able and distinguished naturalist, Professor 

 Edward Forbes, read before the British Association for the Advancement of Science, for 

 1843. Although the views entertained by Forbes with respect to the " provinces of 

 depth " have not been generally substantiated, still his researches were at the time so 

 new and so important that they stimulated in others a desire for further investigation in 

 the same direction. 



This important knowledge is therefore mainly due to the numerous well conducted 

 and equipped dredging-expeditions carried on by private individuals, and by the Govern- 

 ments of leading maritime states. Previous to these investigations the data we possessed 

 with respect to the habitat and range of depth was in most cases erroneous, vague, and 

 unsatisfactory. It was also ascertained that the Brachiopoda are much localised, and that, 

 being very prolific, they usually occur in vast numbers in their favourite haunts. They 

 do not occur everywhere, for throughout a course of 08,890 miles, the "Challenger" 

 dredge was put down at some 361 stations, and Brachiopoda were brought up thirty- 

 eight or thirty-nine times only. In some districts they are specifically numerous, for 

 instance, some thirty species have been got from the Japanese and Corean waters ; but 

 this is the exception, not the rule. 



Dr. Gwyn Jeffreys, who has had much experience in dredging-operations, states in 

 vol. ii, p. 2, of his 'British Conchology,' that " the comparative rarity of Brachiopoda in 

 modern times may be easily accounted for. They mostly inhabit rocky and stony parts 

 of the sea-bed, which cannot be reached by the dredge without great risk of its being 

 lost or injured, although they are gregarious and occur in vast numbers under favorable 

 circumstances. My late friend, Dr. Lukis, found more than 200 specimens of Argiope 

 cistelh'fa on a single stone brought up from a depth of twenty fathoms off Guernsey, and 

 1 myself have repeatedly taken T. caput- serpentis and Crania anomala in such profusion, 

 on the western coast of Scotland, as to be compelled by sheer embarras des richesses to 

 throw away many hundreds overboard in the course of a day's dredging. Even the 

 comparatively rare T. cranium is no exception. I have counted seventy specimens, 



