Jordan and Evermann. Pishes of North America. 1029 



with caducous plates. Vertebra? 39 to 44, 19 -}- 23 = 42 (H. aspro) ; 

 18+22=40 (H. evides); 18 + 22 = 40 (H. scierus) ; 19 + 20 = 39 (H. pJiox- 

 ocepkalua). Parietal region more or less depressed, not strongly convex 

 in cross section ; supraoccipital crest usually present, but small. Pyloric 

 cceca 2 to 4. Coloration bright; often brilliant; sides usually with dark 

 blotches. The most active and graceful of the darters and many of them 

 with most attractive coloration. This group exhibits large variation in 

 minor characters, some of its species approaching very close to those of 

 Etlteostoma, the dividing line between the two genera being somewhat arbi- 

 trary. It seems best not to regard the subdivisions of this group as 

 distinct genera, as the characters which separate them disappear by 

 degrees, (adpof, strong ; Trrepov, fin.) 



. Median line of belly with a series of enlarged caducous ventral plates, which fall off at 

 certain intervals leaving a naked strip from breast to vent; preopercle strictly entire; 

 gill membranes usually separate, sometimes somewhat connected across the isthmus; 

 ventral fins well separated, the interspace usually not less than the breadth of their 

 base. 



ALVORDIUS :* 

 b. Palatine teeth present; dorsal spines 11 to 15; ventral fins widely separated. 



r. Lower jaw as long as upper; snout very narrow and pointed, especially in the adult,; 



space between mouth and gill cleft about % length of head; cheeks and opercles 



scaly; lateral blotches small, quadrate; scales small. PHOXOCEPHALUS, 1418. 



cc. Lower jaw shorter than upper; snout less pointed; distance from mouth to gill 



cleft about half head. 



<l. Snout longer than eye; head very large and long, 3^ in length, chiefly naked; 

 scales very small, about 90; 80 pores; sides with oblong blotches. 



MACROCEPHALUS, 1419. 



GROUP A (ventrals widely separated). 



Percina rex. Hadropterus scierus. loa vitrea. 



Percina caprodes. Cottogaster shumardi. Ammocrypta pellucida. 



Hadropterus aspro. Cottogaster copelandi. Ammocrypta pellucida clara. 



Hadropterus peltatus. Cottogaster gilberti. Boleosoma podostemone. 



Hadropterus ouachitaj. Cottogaster uranidea. Etheostoma swarinanoa. 



Hadropterus macrocephalus. Boleosoma nigrum. Hypohomus aurantiacus. 



Hadropterus phoxocephalus. Boleosoma nigrum olmstedi. Hypohomus cymatotsenia. 



Hadropterus nigrofasciatus. Boleosoma camurum. Hypohomus squamatus. 



Hadropterus roanoka. Crystallaria asprella. 



GROUP B (ventrals well separated, not quite o much so as in A). 

 Hadropterus evides. Ulocentra histrio. Ulocentra stigmaea. 



Etheostoma variatum. Etheostoma elegans. Etheostoma thalassirmin. 



Etheostoma zonale. Etheostoma blenniiis. Boleosoma longimauus. 



GROUP C (ventrals rather close together). 



Psychromaster tuscumbia. Diplesion blennioides. Microperca prceliaris. 



Etheostoma obeyense. Microperca punctulata. Etheostoma squamiceps. 



Ulocentra simotera. 



GROUP D (ventrals very close together, almost touching). 



Etheostoma flabellare. Etheostoma whipplii. Etheostoma pottsii. 



Etheostoma c<eruleum. Etheostoma jessiaj. Copelandellus quiescens. 



Ethcostoma lepidum. Etheostoma rufilineatum. Boleichthys fusiformis. 



Etheostoma cragini. Etheostoma camurum. Boleichthys fusiformis eos. 



Etheostoma australe. Etheostoma maculatum. 



In several of these cases, the assignment is almost arbitrary; thus: Hadropterus mgrofascialus 

 has the interspace narrower than in Hadropterus aspro, and scarcely wider than in Hadropterus 

 evides. Ltiplesion blennioides and Pyschromasler tuscumbia might be placed in Bas properly as in C. 

 We conclude that while this character may prove useful in classification, we are unable to use 

 it to separate a large group or genus, Percina, from the still larger and more heterogeneous group, 

 Ellteostoma. 



* Named for General Benjamin Alvord, U. S. Army, a gentleman interested in natural history, 

 who discovered "Alvordius maculatus," at Fort Gratiot on Lake Huron. 



