The most positive characters distinguishing the species is found on the disc of the underside of forewings. 1. _M. montana_, has the disc uniform fulvous the markings of the upper-side shining through the coloration of the disc. 2. _M. collina_, has the disc orange color; markings very perceptible and towards the exterior margin bordered by a series of black spots. 3. _M. campestris_, has the disc with a yellow spot between the first and second primary costa, and is bordered towards the exterior margin by an angular row of yellow spots, which are themselves bordered at the inner side by deep black. 4. _M. pratensis_, has the disc ochre yellow with irregularly diluted spots and some black marks near the _posterior_ margin. There are plenty of other points of difference, as may be seen by comparing the diagnoses. But for recognition of any of the species it is sufficient to examine the disc. The other differences are difficult to describe, as all those who know by their own experience the difficulties of analyzing the complicated markings of the underside of the hindwings in this group will testify. As to the larval state of these insects nothing is known, and this want of facts regarding their metamorphosis, is the more to be lamented as the natural affinities of this type are by no means very clear or simple. It seems to constitute a kind of intermediate group between the true _Melitæae_ and the Arctic type of _Argynnides_. The eyes are more prominent than in the typical species of Melitæa, and I find a similar conformation of the head in _M. Tharos_ from the Atlantic States. At the same time the underside of the hindwings of all these species does not represent the well-defined alternate bands of the typical _Melitæae_, but the intricate undulations and undefined lights and shadows of the underside of the Arctic type of _Argynnis_. In fact _M. montana_ approaches in this respect very closely to _A. Aphirape_. TYPE II. This type corresponds to the European type of _M. Athalia_, and even in the differential characters of the four species known to me there is a striking parallelism to those of four European species, so that each of them looks as if it was the transposition of a foreign species separated by a peculiarly Californian character, afterwards to be pointed out, from its European congener, and separated amongst themselves by the very same characters that separate the four European parallel species from each other. Their analogies are as follows: _California._ _Europe._ M. PALLA, M. DICTYNNA, M. WHITNEYI, M. ATHALIA, M. GABBII, M. PARTHENIE, M. HOFFMANNI, M. ASTERIA.