Striæ interrupted by a hyaline furrow on each side of the median line kinsmanii Striæ not interrupted: Loculi, five, or less exigua more than five, equal, ending at distance from the ends smithii ending near the ends, distinct lanceolata indistinct elegans very numerous apiculata unequal angulata {87}Karsten states that there are two chromatophores, each of which extends from the middle of one valve to the end and down the middle of the other valve. Mereschkowsky says, however, that there are four plates or chromatophores, sometimes on the valve, sometimes on the zone, according to the species, and that two long pyrenoids unite the two opposite chromatophores. MASTOGLOIA KINSMANII LEWIS Valve lanceolate-elliptical, with sub-rostrate ends; loculi more numerous than in M. angulata but less than in M. apiculata, the middle ones larger. Median line with a sulcus on each side; central area quadrate. _Mastogloia braunii_ Grun. (According to Cleve). Atlantic City. Pl. 17, Fig. 16. MASTOGLOIA EXIGUA LEWIS Valve elliptical- or linear-lanceolate; loculi, 2-5, usually 3, larger in the middle and rounded; central space small; striæ, 20-24 in 10 µ. Along the coast. Pl. 17, Fig. 24. MASTOGLOIA SMITHII THWAITES Valve lanceolate, sub-rostrate; loculi forming a wide band ending at a distance from the ends; striæ transverse, with puncta forming longitudinal rows; central area rounded or transversely elliptical. Along the coast. Pl. 17, Fig. 19. MASTOGLOIA LANCEOLATA THWAITES Valve lanceolate, with sub-rostrate apices; loculi very numerous; median and central areas indistinct; striæ, 19 in 10 µ, punctate, convergent at the ends. Along the coast. Pl. 17, Fig. 18. MASTOGLOIA ELEGANS LEWIS Valve lanceolate, acute; loculi indistinct or rudimentary, extending to the ends; central area apparently quadrate, sometimes indistinct; puncta distinct, 15 in 10 µ, in transverse and longitudinal rows. Along the coast. Common. Pl. 17, Fig. 20. MASTOGLOIA APICULATA WM. SM. Valve elliptical-lanceolate, sometimes with slightly produced apices; median line between two ribs; central space very small; loculi numerous; puncta in slightly radiating rows and in longitudinal lines. Along the coast. Pl. 17, Figs. 21, 22, 23. MASTOGLOIA ANGULATA LEWIS Valve elliptical, with produced apices; loculi usually less than 12, unequal, the larger in the middle; striæ, 12 in 10 µ, puncta in decussating rows. "Differs from apiculata in its more broadly elliptical shape, the smaller number of its loculi and the angular character of its striation" (Lewis).