NATURAL SCIENCES OF PHILADELPHIA. 359 



tral region of the interambulacral areas. The depression, however, also in- 

 cludes the two marginal rows of each interambulacral series. There is like- 

 wise a faint narrow, almost linear, impression on the internal cast, extending 

 trom the apical disc about halfway down the middle row of plates in each in- 

 terambulacral field. 



This form can be at once distinguished from 0. Danx, the only other known 

 s[>ecies of this type, by its proportionally much larger and less numerous in- 

 terambulacral plates, of which there are only_^'y« instead of eight or nine rows 

 to each area. Its arabulacral areas are also proportionally narrower, and, as 

 already stated, differ in not being furrowed along each side, with a ridge along 

 the middle. 



As we have elsewhere suggested, the group Oligoporus seems to be exactly 

 intermediate in its characters between Melonites, Owen and Norwood, and Fa- 

 ln'.chinus, (Scouler) JlcUoy. That is, it differs from Falsechinus in having four 

 rows of arabulacral pieces and four double rows of pores, instead of livo of each, 

 as well as in having the arabulacral areas more or less sunken below the in- 

 terambulacral fields. In the last character it agrees more nearly with Meloni- 

 Us, from which, however, it differs widely in having on\\ four rows of arabula- 

 cral pieces and/o?<r double rows of pores instead of ten of each to each area. 

 In the nature of its apical disc the species under consideration shows that in 

 this type it agrees well in its general characters with Melonites. "We also know, 

 from a crushed specimen of Oligoporus Daniv, that the species of this group 

 have the jaws very like those of Melonites. The question may therefore arise 

 whether or not these differences in the number of pieces and pores of the ambu- 

 lacra are of generic importance, and whether we ought not to regard them as 

 only subgeneric and call our species Melonites [Oligoporus) nobilis. On the 

 same grounds, however, we would have as good reason to regard both Oligopo- 

 rus and Melonites as mere sections or subgenera of Faliechinus. We cannot^ 

 however, believe so important and constant a difference of less than generic 

 value, no gradations being yet known in this character between Oligoporus 

 and Melonites ou the one hand, or between the former and Faluchinus on the 

 other. It is true we yet only know one species of Melonites, but we now know 

 two well marked species of Oligoporus, while there are eight or nine known dis- 

 tinct species of Falsechinus, all of which latter agree in having but two rows of 

 arabulacral pieces to each area. 



At the time we proposed the name Oligoporus we were not aware that Prof. 

 Desor had designated a section (not a genus) of the family Cidaridx by the 

 name Olu/opores. In case this should be regarded as a serious objection to 

 our name Oligoporus we suggested, in the second volume of the Illinois Geolo- 

 gical Reports, the name Mehnopsis for this group instead ; and if it should be 

 adopted, the species here described would have to be called Melonopsis nobilis. 

 The name Oligopores, however, from its different termination, we should think 

 sutficienily distinct. 



Locality and position. — Calhoun County, Illinois, from the Burlington divi- 

 sion of the Lower Carboniferous series. 



Description of Seven New Species of AMERICAN BIRDS from various locali- 

 ties, with a note on Zonotrichia melanotis. 



BY GEO. N. LAWRENCE. 



1. DeNDRCECA CAPITALI.S. 



Male. Front and crown of a deep rich reddish brown ; back and smaller 

 wing coverts yellowish olive-green, becoming more yellow on the rump ; 

 central tail feathers and the outer webs of the others dark olive-brown, edged 

 the color of the back, the inner webs of all except the central tail feathers 

 are yellow; the quill feathers and the larger wing coverts are blackish brown, 

 the primaries and secondaries with margins the color of the back, the terti- 



1868.] 



