Crustacea of St. Andrews. 259 



num in the laminarian region strikes even a superficial observer 

 of the group ; while the large number of rare and new spe- 

 cies which were met with during the frequent dredgings of 

 Mr. Gwyn Jeffreys and the Rev. A. M. Norman still further 

 heightens the contrast. The southern region, again, is boldly 

 separated by the presence in large numbers of Gymodocea 

 truncata and Sjjhceroma Prideauxianum in the fissures of 

 rocks between tide-marks, and Dynamene in rock-pools. 

 The characteristic Tanais vittatus, Paranthura costana, Ncesa 

 bidentata, Mcera grossimana, Chelura terebrans, Gonilera cylin- 

 drica, and the large Cymothoa parasitic on the fishes at once 

 distinguish the fauna of the Channel Islands from that at 

 St. Andrews. The rarity of Orchestta littorea at the latter 

 and its abundance in the tidal region of the Outer Hebrides 

 is another interesting contrast. 



Many of the sessile-eyed Crustacea, such as Talitrus locusta, 

 are extremely hardy. Gammarus locusta is often found in 

 putrid localities, and it survives almost every other marine 

 form in putrid vessels in confinement. The group as a whole 

 is composed of extremely active animals ; and even the most 

 grotesque, such as Caprella tuberculata, are at home in the 

 intricacies of Ceramium and other finely branched seaweeds. 

 The boring forms (by jaws) are represented by Limnoria 

 lignorum ; but its depredations are comparatively insignificant, 

 probably because little wood is employed within water-mark in 

 the construction of the harbour. The perforations of Talitrus, 

 again, abound in the sand, and the looped burrows of Coro- 

 johium in the sandy mud of the flats it inhabits. The nest- 

 forming crustaceans are represented by Amphithoe podoceroides, 

 Siphonoecetus typicus, Podocerus variegatus, and P.falcatus; 

 while the young of Gammarus locusta are often observed 

 adhering to the abdominal region of the parent. 



The Cirripedes occur abundantly between tide -marks, the 

 most conspicuous being Balanus balanoides, which covers 

 the bare rocky ridges opposite the Castle and other parts. 

 In deep water the various species are attached to shells, 

 stones, crabs, wood, cork, coal, tests of ascidians, and other 

 structures. 



I am indebted to Mr. Spence Bate for the determination of 

 several doubtful forms, and especially to the Rev. A. M. 

 Norman for his courteous assistance in this respect, and in 

 revising the list. Mr. G. S. Brady kindly furnished me with 

 the names of the Ostracoda occurring in shell-debris on the 

 West Sands and other collections. 



IS* 



