ON THE GENERA IN THE APATELID.E ( = ACRONYCTIDiE). ^97 



tional differences in the imagines than I then did ; venosa is closer 

 to rumicis than rumicis is to menyanthidis, or any other species of 

 Viminta {Pharetra). He divides my Guspidia into two genera, 

 Apatela and Hyhoma. If I divided them at all, I should divide 

 them into a larger number of sections ; but if you divide them only 

 into two, then Mr. Grote's divisions are as good as any others I could 

 suggest. 



Apatela would have newly-hatched lauva with abnormal seg- 

 ments 6, 10, and 11 pale. Pupa with numerous spines to cremaster. 

 The NEWLY-HATCHED LAUv.E of Hi/b<iiiia would have 6 and 7 either both 

 pale or both dark, and the pupa with few spines to the cremaster. 

 Megacephala has nearly as numerous spines as leporiua, and is 

 nearest to this group of the Hyhoma, Hiibn., section of Mr. Grote. 



Of the other genera that Mr. Grote includes in ApATELmj-:, I 

 incline to allow orinn to be near Acronyrta, owing to the weak 11th 

 segment of the newly-hatched larva. 



Demas I prefer to place with Liparid.e, as also cocnobita and 

 ludifica, of which, however, I have had too little material for study to 

 make my opinion of much value. All these — oriou, coryli, coenobila, 

 ludifica — differ from Acronycta proper, in having spherical instead of 

 flat eggs, and from typical Liparidae, in the eggs being very distinctly 

 ribbed. 



To return to Mr. Tutt's question, 1 fear I shall disgust him, by 

 saying that the question of genus or sub-genus is more a personal 

 than a scientiKc one. A genus is a group of species, and the chief 

 determining factor is that of size and convenience. When you 

 classify say, the Noctuides, you make groups of convenient size, then 

 you try to form a measure of the difference between these several 

 groups ; you then rearrange the groups, so that the difference between 

 any two contiguous groups shall be of about the same value as those 

 between any other two groups. Here and there you have a species 

 so isolated that it unquestionably forms a genus by itself, elsewhere 

 you have groups so large that you try to sub-divide them, and have 

 to be satisfied to do so on less important characters than, as a rule, 

 you like. The Acronyctas are a portion of the Noctuides, on the 

 classification of which Mr. Tutt is an expert, and I am not ; but look- 

 ing to the very slight characters that separate some accepted genera 

 amongst the Noctuidks, 1 should imagine that not only are Guspidia, 

 Viminia and Blsuhia, good genera, but that Cuxpidia must be sub- 

 divided into genera much like the sub-genera into which Mr. Grote 

 divides this section. 



Mr. Tutt may say that my description of how you arrive at genera 

 is not in accordance with fact. Few systematists assume for them- 

 selves so clear a field to start with as my description implies ; but I 

 think, with this circumstance in view, my description is correct ; and 

 that, therefore, in the case of a genus of NocTumEs, it falls rather to 

 Mr. Tutt than to me to say whether the distinction between the 

 groups are of generic value, as it is estimated amongst the Noctuides. 



1 have, however, much sympathy with those who object to sub- 

 genera altogether ; call a group a genus or leave it alone. Anything 

 that is worth separating under a name is a genus. 



