300 Part III, — Ninth Annual Report 



V.— ADDITIONS TO THE FAUNA OF THE FIRTH OF FORTH. 

 Pakt III. By Thomas Soott, F.L.S. 



Forty-two species of Crustacea and one species of Mollusca are in this 

 paper recorded for the Firth of Forth. Though several groups of the 

 Crustacea are represented among those now recorded, by far the greater 

 part belong to the Copepoda, of which there are 31 species, while the 

 Ostracoda, Cladocera^ Amphipoda, Isopoda, and Schizqpoda are each 

 represented by 1 species, and the Decapoda by 3. 



It will be observed from this and previous papers that the Firth of 

 Forth possesses a rich crustacean fauna. Previous to 1887 about 120 

 species had beeu recorded for the Forth ; whereas now there are, including 

 those mentioned in the present paper, about 370 species, besides several 

 which are still undetermined. But though the number of species has 

 within recent years been considerably increased, I do not think it can yet 

 be considered as approximately representative of the crustacean fauna of 

 our estuary; and I venture to predict that when the Firth of Forth 

 becomes more thoroughly and systematically worked up the number of 

 Crustacea will be little, if at all, short of 500 species. . 



COPEPODA. 

 GNATHOSTOMA. 



Calanidjj, 

 Metridia armata, Boeck. 



1865. Metridia armata, Boeck, 'Oversigt over de ved Norges 



Kyster iagttagne Copepoder,' p. 14. 

 1873. Paracalanus hibernicus, Brady and Robertson, 'Ann. and 



Mag. Nat. Hist.,' ser. 4, vol. xii. p. 126, pi. viii. figs. 1-3. 

 1878. Metridia armata, Brady, 'Mon. Brit. Copep.,' vol. i. p. 42, 

 pi. ii. figs. 1-12; pL lvi. figs. 19, 20. 



Habitat. — In various parts of the Forth, between Inchkeith and May 

 Island, I have obtained this species several times during the past year 

 with both the surface and bottom tow-nets, but not very common. It is 

 readily distinguished, especially the female form, by the elongated joints 

 of the abdomen, and several of the first joints of the anterior antenna 

 being strongly toothed on the upper edge. 



Acartia discaudatus, Giesbrecht. 



1881. Dias discaudatus, Giesbrecht,* 'Die Freilebenden Cope- 

 poden der Kieler Foehrde,' p. 148, pi. iii. figs. 4, 22, 23; 

 pi. v. fig. 18; and other plates. 



Habitat. — Between Portobello and Cockenzie, well inshore. I obtained 

 several specimens of this species ; the peculiar form of the caudal furca 

 first attracted my attention. In the female the last abdominal segment is 

 much broader posteriorly; the furca are broad flattened plates, which 

 together are in breadth about equal to the length of the furca and last 

 abdominal segment. This appears to be the first British record of Acartia 

 discaudatus. 



* Fierier Bericht der Commission zur mssenschaftlichen Untersuchung der deutschen 

 Meere, in Kiel, 1887-1881. 



