PACKARD.] EEPRODUCTIVE HABITS OF BRANCHIOPODID^. 423 



The indirect factor of tlie red color^ (or green, of others) of Eiibran- 

 chipus I assume to be microscopic organisms contained in the soil of the 

 ponds, primarily and gradually acted upon by quercitaunic acid or tan- 

 nates and humus. 



I have grave doubts whether to regard the pale races, set B, as par- 

 tially starved individuals, since their nourishment consists of organic 

 matter contained in the mud. The latter is taken up in precisely the 

 same manner as known in the European Branchipus stagnalis, i. e., by 

 striking with the occipital part of the head against the mud, thus filling 

 through the agitated mud the ventral median canal between the bran- 

 chipeds, and thence by gradual paddling, the mud will pass therefrom 

 toward the head and mouth. The contents of the alimentary system, 

 as examined, also correspond with this manner of feeding. They will 

 never partake of any kind of food thrown into the water. (The pale 

 races had not reached sexual maturity had they not had food enough.) 

 Sesquichloride of iron did not indicate even a perceptible trace of 

 quercitannic acid in the clay- water of the isolated pool, but such was 

 the case with the brownish clear water of the surrounding i)onds in- 

 habited by the normal large and red Eubranchipus. 



The slightly milky water of the isolated pool owes its color to finely 

 suspended clay-particles, and, I should judge, although I have neglected 

 to microscoijically examine the same, contains comparatively more or- 

 ganic matter, adhering to the inorganic particles, than the clear water 

 of the other pools. This is contrary to the assumption that the pale 

 races were partly starved individuals, 



I rather draw the inference, that we here liave both, a difference in 

 quantity, and quality of nourishment, the former preponderating, the 

 latter indifferent as to color. The contents of the alimentary system of 

 Branchiopods are for the greater part a fine soft magma of mud inter- 

 mixed with oil-globules, the latter being the secretion of the wall-glands 

 of the canal. 



Very likely specimens living in water with finely dispersed mud or 

 clay, have less trouble in getting their food, the nourishment being more 

 uniform and already so fine that it needs not to be masticated or sepa- 

 rated from coarser particles.^ 



Bemarlcs on the cephalic scute or Kopfschild. — Is not the larval cephalic 

 scute^ (in our form $ of set B, preserved in the adult) a rudiment of 

 the two valves of the Estheridse'? In that family two or three thoracic 

 segments serve for the insertion of the bivalvular duplicature.' 



Mode of copulation of pale race of Eubranchipus vernalis. — The copula- 

 tion between males of set B with females exhibiting the two forms of 

 claspers illustrated by figures 61, A, B, lasts from 3 to 4 minutes, but many 

 unsuccessful attemx^ts to accomplish the same are usually made, often end- 

 ing with the escape of the females, owing to the check caused by the crossed 

 claspers. In both the red and white race the attempts were never made 



1 An interesting note on cliloropliyll and protection of colorless cells as an absorbent 

 of certain light-rays is to be found in Ainer. Nat. March, 1880. 



2 Mr. E. P. Austin — Amer. Nat. X (Aug. 8, 1876), page 508 — mentions that in March 

 he obtained 28 different species of Dytiscidaj from a small clay-pit which had been 

 filled with water. Some of the species occurred in immense numbers. 



Hermaphroditism, Amer. Nat. March, ld80, page 200. — Hermaphroditism seems to 

 be a thraldom necessary at the outset, but from which all living things are seeking 

 to escape. (Sexual differentiation in Epig£ea repens, by Lester F. Ward, A. M.) 



^Spangenberg, loc. cit., page 14, Taf. I, Fig. 1, and also Dr. Carl Clans, "Zur 

 Kenntniss des Baues nnd der Eutwicklung von Branchipus stagnalis und Apns cancri- 

 formis." Gottingen, 1873, Taf. II, Fig. 5, D. P.; also same author in "Beitriige zur 

 Kenntniss der Entomostraken." Marburg, 1860, I. Heft ; also Dr. A. S. Packard in 

 "Phyllopod Crustacea," and same author in "Cave Fauna of Utah and descr. of new- 

 spec, of Crust." 



