7. 



ioo6 General Notes. . [December, 



(^From the American Naturalist^ December^ 1882.) 

 ZOOLOGY. 

 A NEW GENUS AND SPECIES OF THE CRUSTACEAN FAMILY LyNCO- 



DAPHNiNiE.^ — Lyncodaphnia, gen. n. (Plate xvi, Fig, 1-4). Form 

 much as in species of Alonella, etc., truncate behind ; superior 

 antennas Hke Macrothrix, attached movably to the end of a blunt 

 prominence beneath the head ; second or swimming antennae 

 slender, four-jointed ramus with three long setae and a stout thorn 

 at the end of distal segment, the joint following the short basal one 

 with a thorn above, the following joint unarmed (!); three-jointed 

 ramus as in Macrothrix, the basal segment armed with a much 

 elongated seta ; eye relatively small, pigment fleck {macula nigra) 

 present ; intestine twice convoluted, expanded in front of the rec- 

 tum, opening in the " heel " of the post-abdomen; post-abdomen 

 slender, sub-triangular, margined behind with a double series of 

 spines ; terminal claws large, and furnished with a long and short 

 spine near the base ; shell margined below by stout movable spines. 

 Few more interesting forms than the one forming the type of 

 this very peculiar genus have been found, since it combines in a 

 curious manner those characteristics hitherto regarded as distinc- 

 tive of the families Daphnidae and Lynceidae. Kurz says '} *'Keine 

 cladocerenfamilie bildet eine so streng in sich abgegrenztes natiir- 

 liches Ganze, wie eben die Lynceiden," and this after recognizing 

 the relationship of Macrothrix and Lathonura to the Lynceids, 

 by placing them in the sub-family Lyncodaphninae. The form 

 above referred to, however, has quite as close affinity to the Lyn- 

 ceidae as to Macrothrix, though it resembles the latter rather 

 more on a superficial examination, indeed if one were to divide 

 the animal back of the heart and examine the two portions inde- 

 pendently, it would be impossible to avoid referring the head to 

 Macrothrix and the body to some Lynceid genus. Thus is fur- 

 nished another of those curious intermediate forms which remind 

 us that the possibility of distinguishing families and genera, lies 

 alone in the meagerness of our knowledge. 



There can be no doubt that this genus should stand next to 

 Macrothrix, but it will be necessary to modify a little the diagno- 

 sis of the Lyncodaphnidae to receive it, and it then appears that 

 it cannot longer remain a sub-family of the Daphnidae, hence I 

 have proposed to give it equal rank with that body and the Lyn- 

 ceids as an independent family, Lyncodaphninae, including the 

 genera Macrothrix, Lyncodaphnia, Drepanothrix, Lathonura 

 (= Pasithea), Ilyocryptus. As thus limited a very natural group 

 is formed, in size and isolation corresponding well with the other 

 related families. 



^Series secunda generum (Daphnidre), P. E. Miiller, Danmaik's Cladocera, p. 134; 

 sub-family Lyncodaphnincc, Kurz. Dodekas neuer Cladoceren, p. 24. 



■■^Kurz. Dodekas neuer Cladoceren nebst einem kurzcn Ubersicht der Cladoceren 

 fauna Bohmens, p. 30. 



IRLSOII 



