394 ON THE FAUNA AND BOTTOM-DEPOSITS NEAR THE 30-FM. LINE 



scarce. I imagine that the scarcity of species of this habit is due to 

 the fineness of the sand, and there are two ways in which this might 

 be detrimental. Either the general nature of the sand might be too 

 loose to afford a satisfactory hold, or the absence of larger particles 

 mixed with the fine sand might prevent the embryos from fixing in 

 their earliest stage. A comparison of the composition of the sand 

 on this ground with that on Ground I. shows that they differ in two 

 ways. There is a smaller percentage of medium and coarse sand on 

 Ground II., but at the same time there is a somewhat smaller propor- 

 tion of silt. The first of these differences might make it more difficult 

 for the embryos to fix, whilst the second might tend to make the sand- 

 particles bind together somewhat less firmly. 



Of the other fixed species Sertularella Gayi is not uncommon, fixed 

 generally, as on the inner trawling ground, to the tube of the polychajte 

 Thclejnis (cincinnatus ?), and the abundance of Sertularia ahidina, which 

 is not present on the inner ground nor on the Eddystone Grounds, 

 is a characteristic feature. I have not satisfied myself as to the mode 

 of attachment of this species on the present ground, the specimens 

 examined for this purpose not having afforded evidence on the point. 

 On the Sertularia the creeping variety of Lofoea dnmosa and the 

 hydroid Coppinia arda are plentiful, as well as a species of Foraminifera 

 {Trimcatulina lohatula) tubes of Sinrorhis and the Polyzoa Cellepora 

 avicularis, Cellepora ramulosa, and Idmonea serpens. Plinmdaria 

 Catharina is fairly plentiful on the ground, and as will be seen from 

 the list several other hydroids are occasionally taken. 



Three other fixed species are characteristic of Ground 11., viz., 

 Alcyonium digitatum, large colonies of which are abundant, fixed often 

 to Cardium ecliinatum shells ; Chondradinia digit ata, fixed to the same 

 kind of shells ; and Epizoanthus incrustatus in its free form (see 

 Haddon, No. 35, p. 638), which is constantly taken. 



Ascidiella scahra attached to Sertularella Gayi was not plentiful, 

 whilst a few Ciona intestinalis fixed to shells are recorded. The few 

 shells which are present are generally free from encrusting Polyzoa. 



Wandering sjyecies. Ophiura ciliaris is present in moderate numbers, 

 but only a few small specimens of Ophiothrix fragilis, clinging to the 

 roots of hydroids, were seen. Asterias ruhcns and A. glacialis were 

 often represented by large specimens. Of Crustaceans Galathea dispersa, 

 Eiqxigurus Bernhardus, and Anapagurtis Icevis were constantly taken, 

 together with occasional specimens of Stenorhynchus longirostris, Inachus 

 dorsettensis, and Eurynome aspera, A few fair-sized Pecten opercularis 

 were obtained in two of the hauls. Fishes were very scarce, the three 

 species represented being Trigla pini, Trigla gurnardus, and Baia 

 davata, of which only a few specimens were taken. 



