96 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



of the families is represented by only a few species, I am unable to 

 attempt improvements in the classification of any of them. In a pre- 

 vious paper — Isopoden, Cumaceen und Stomatopoden der Plankton- 

 Expedition (Ergebnisse der Plankton-Expedition der Humboldt-Stiftung, 

 Bd. 11. G. c) — I have proposed a partly new arrangement of the Iso- 

 poda, with observations on some of the families, and to this treatise 

 the reader must be referred for several particulars. I have thought it 

 useful to illustrate all the species rather fully, and to describe them 

 in some detail, taking into consideration the best representations in the 

 literature, yet altering and adding where it seemed advisable. 



ASELLOTA. 



Of this large tribe only two species were sectu'ed. Both belong to the 

 Munnopsidae G. O. Sars, a family rather badly limited, and both must be 

 referred to the genus Eurycope G. 0. Sars. Unfortunately, the material is 

 rather scanty and all the specimens are much mutilated, yet I am able to draw 

 attention to a point of significance, namely, that the genus with the limits 

 still adopted presents startling differences in the structure and shape of the 

 mandibles of some of the species. In the two species here described the 

 mandibles possess distally a cutting portion, behind this a " lacinia mobilis " ^ 

 ■with a row of setae on each mandible and a strong " cuspis lacinise " on the 

 left one, and farther backward a well developed molar process. In the small 

 Norwegian species the mandibles seem to be of similar structure,^ but in the 

 large Eunjcope gigantea G. 0. Sars they are very different. In this species 

 each mandible has a very long oblique edge on the inner side, the molar process 

 is very short and badly defined, no lacinia mobilis is found, etc. It may be 

 adtled that the two pairs of jaws also present differences from those in the 

 species to be described here. (The mouth organs of Eurycope gigantea were 

 first described by G. O. Sars in the Norwegian North-Atlantic Expedition, 

 Zool., Crustacea, Vol. I. pp. 132, 133, Plate XI. Fig. 10-14, and shortly after- 

 wards by the present author in his account of the Crustacea in Dijmphna- 

 Togtets zool.-bot. Udbytte, 1877, pp. 199-201, Tab. XX. Fig. 3c- 35^.) It is 

 interesting to observe that great differences in the structure and armature of 



1 This and the following term are set forth and explained in my paper : Ciro- 

 lanidae et Fam. nonn. prop. Musei Haun. (K. Danske Vidensk. Selsk. Skrifter, 6 

 Reekke, naturv.-math. Afdeling, V. pp. 2.39-426, Tab. I.-X.) 



2 At my request, Prof. G. O. Sars very kindly sent me the proof-sheets containing 

 the account of the Munnopsidse, in his new leading work on the Isopoda. He has 

 divided the family into two families, etc., but he still maintains the genus Eurycope 

 in its old and very wide extension, yet remarking that some of the species estab- 

 lished by Beddard "ought perhaps more properly to be separated as types of 

 nearly allied genera." 



