Alae anticae subtus aurantiacae apicem versus luteae. Macula disci et fascia intermedia infracta luteae, haec intus nigro marginata. Alae posticae subtus luteae, linea transversa undulata divisae; A radice usque ad lineam transversam brunneo signatae et prope mediam lineam transversam umbra obscura indutae; quae umbra extenditur usque ad seriem punctorum. Lunula inter quintam costam et sextam candida, aucta et umbra amplexa. This species is very common in different localities, especially on marshy places, where Hemizonia abounds. Seems to be peculiar to the lower regions, and produces several annual generations. 4. _M. pratensis_, Behr, n. sp. Alae supra nigrae fasciis macularibus fulvis instructae. Maculae fasciae submarginalis alarum posticarum singulae singula puncta nigra gerentes. Alae anticae subtus ochraceae maculis pallidioribus hinc et illinc signatae. Marginem versus posticam extant aliquot maculae nigrae. Alae posticae subtus hepaticae lineis undulatis, maculis, umbris serieque punctorum cunctis aeque brunneis instructae. Lunula submarginalis vix pallidior et umbra amplectente tantum e reliqua ala discerni potest. This species is found on grassy hillsides and is common enough in some localities near San Francisco. Several generations are found from spring to the beginning of the rainy season. Before I had a sufficient series of these nearly allied species in my possession, I considered them local varieties of one single species. Afterwards I had an idea that two of them, _M. collina_ and _pratensis_ might be seasonal varieties or alternating generations, like for instance _Arachnia Prorsa_, whose vernal generation _A. Levana_ was for a long time considered another species. But according to my observations continued through several years, these species are not confined to certain seasons, but are to be found throughout the dry season. If they were alternating generations of the same insect the different forms would be found only at certain seasons; but such is not the case. _M. montana_ is very variable but never approaches to the characters of the other three species. The rest are as constant as a species can be, and in a long series of duplicates from different localities I do not find anything like an intermediate form. The four species of this type agree in the following points: 1. A row of dots between the first and second transverse lines of the hindwings, in the space that represents in these species the submarginal fascia. This row is clearly visible on both sides. 2. The marginal lunula between the fifth and sixth vein is perceptibly augmented on both sides, and on the other side is frequently of lighter color and always surrounded by a deeper shade.