REPORT ON THE AMPHIPODA. 419 



The expressions " les fausses x'attes IrancMcdea " and " les faasses pattea ahdominales on les 

 organes de la respiration " would appear to be incorrect ; if accurate, they would he 

 inconsistent with the arrangement of this genus in tlie order Amphipoda. That one species 

 of the genus should have a pleon of only two segments, while its congeners have the five 

 segments which are the normal number for the pleon among the Hyperina, is a very strange 

 peculiarity. But as to this and other points, see additional Note on Hesse, in Appendix. 



1873. LtJTKEN, Chr. Fr. 



Bidrag til Kundskab om Arterne af Slaegten Ci/amits Latr. eller Hvallnsene. 

 Med 4 Tavler og et fransk Eesume. Videusk. Selsk. Skr. 5 Eaekke, natnrviden- 

 skabelig og mathematisk Afd. 10 B. III. Kjobenhavn, 1873. (Memoires de 

 I'Academie Royale de Copenhague. 5"" seiie. Classe des Sciences Vol. X. iVo. 3.) 



After repeating the observations on Cyairms which he had made in 1860, Liitken gives an 

 exceedingly valuable report \vgon the historical development of our acquaintance with the 

 group of Crustacea, which are called whale-Hce. From Frederik Martens in 1675 to the 

 date of his own work, Liitken's vigorous research can scarcely have let any statement of 

 importance on the subject escape him, or any serious error pass the ordeal of his criticism 

 without correction. 



The definition he gives of Ci/amus, Latr., is as follows : — 



" Corpus cras.mm, havd laminare. Pedes pnimi parts minuti, sub pedibus secundi parts fere vel 

 omnino ahsconditi ; ammlus corporis primus a capite indistincte sejundus vel aim hoc plane 

 confivsns. Pedes maxillares quinque-articulati. (Mares foeminis vidgo majores.)" 



The species described are, 1. Cyamus m.ijsticeti, Ltk., from BaJsena mysticefus, the common, or 

 Greenland Whale; 2. Cyamus monodontis, Ltk., horn Mo7iodo7i monoceros, the Narwhal; 



3. " Cyamus Kessleri," Brandt, " coming from the northern part of the great eastern ocean, 

 probably from a true whale of the group of Balama ausfralis and Balssna biseayensis" ; 



4. Cyamus erraticus, Roussel de Vauzkne, from Balxna ausfralis, the Cape Whale; 5. 

 Cyamus boopis, Ltk., the Oniscus ceiioi 0. Fabricius, 1780, from the Northern Hump-back, 

 the Krepokak of the Esquimaux, Mnjaptera boops, and possibly parasitic on other species of 

 MegaiJtera ; 6. ? Cyamus pacificus, Ltk., from a whale (of unknown genus and species) in 

 the Pacific in the neighbourhood of Panama, a species nearest iu form to Cyamus boopis, 

 but also near to Cyamus erraticus; 7. Cyamus ovalis, Rouss. de Vauz., from protuberances 



- on the head of Balxna australis and from the North Pacific " Sletbag " [Balxna japonica ?}; 

 8. " Cyamus Rhytinx," J. F. Brandt, Steller's species, for which Brandt proposed a new 

 genus Sirenocyamus, and which Liitken agrees with Brandt in thinking possibly akin rather 

 to Proto than to Cyamus; 9. Cyamus nodosus, Ltk., the Oniscus ceti of the Zoologia 

 Danica, III. p. 69, pi. 119, f. 13-17, 1789, from the Narwhal, Monodon monoceros; the 

 name " Cyamus Belugse " sometimes given to this species being rejected by Liitken as 

 grounded on the mistaken supposition that the creature is also a parasite of DelpMnapterus 

 beluga; 10. Cyamus globicipitis, Ltk., a species already noticed as possibly new, but not 

 named, by Steenstrup in 1843 [nS50], parasitic on the Caaing, or Pilot Whale, Globio- 

 ceplicdus melas ; 11. CyamMS gracilis, Rouss. de Vauz., from the protuberances of the head 

 oi Balse.na ausfralis and Balxna japonira? ; 12. Plafycyamus fhompsoni, Gosse, parasitic 

 on the Bottlehead, or Beaked Whales, Hijpcroodon rostraliis and Hyperoodon lafifrons. 



The new genus, Plafycyamus, instituted to receive Gosse's Cyamus thompsoni, is defined as 

 follows : — 



" Corpiis valcle depressum, laminare fere; pedes primi paris pedes secundi paris magnitudine 



