OCULAR AND GENITAL PLATES. 137 



one has I, IV, and four have I, V, II insert. Specimens from this locaUty make an approach in 

 primitiveness of structure to that shown in the 5 to 10 mm. series from Dumphng Islands, as 

 regards the percentage of I, and I, V insert; also in both there are no cases of I, V, IV insert, 

 but a considerable number of I, V, II. The Gullmar specimens are peculiar as in all individuals 

 the spines are of a light purplish color with only an indication of the usual green. At Dumpling 

 Islands the specimens are typically bright green; but in eight or ten out of the series there 

 collected the spines are light purplish, so close to the Gullmar typical color that a specimen 

 placed with them could not again be selected by its difference. 



The next step in advance is found in a series which I collected at Pulpit Harbor, North 

 Haven, Maine. This locality is a deep, very narrow bay, well removed from the open ocean. 

 It receives fresh water from a considerable lake at the head of the bay and also by leaching from 

 the shores, so that the water is distinctly brackish. The water is shallow, and the Echini, 

 which are extremely abundant, were collected at low tide near the bridge which crosses this 

 narrow bay. All individuals below 30 mm. in diameter were eliminated, and those tabulated 

 ranged from this size up to 58 mm. in diameter. In this series (1,700 specimens) 10% have 

 ocular I only insert, one specimen has ocular V alone insert; 88% have oculars I, V, and 0.5% 

 have I, V, IV insert. This is a large percent of arrested and small percent of progressive variants 

 for the species. The aberrants are 1%. Of these, three specimens have oculars I, II insert; 

 four have I, IV; one has V, IV; and six I, V, II insert. As a whole, the Pulpit Harbor series 

 makes a fairly close approach to the character seen in the immature 15 to 20 mm. series from 

 Dumpling Islands, the similarity being in the percentages of the several characters and the 

 relatively high number of aberrants with oculars I, V, II insert (table, pp. 142, 143). 



A number of Strongylocentrotus drobachiensis dredged off St. Pierre, south of Newfoundland, 

 at the mouth of the St. Lawrence River, were kindly given to me by Mr. Owen Bryant. Of this 

 lot (194 specimens), all good sized individuals, 6% have ocular I only insert, 92% I, V, and 

 0.5 % I, V, IV insert. The aberrants are 2 %, one specimen having I, IV and two I, V, II insert. 

 The specimens of this locality are closely equivalent to the 20 to 30 mm. series from Dumpling 

 Islands, as regards the percentage of inssertness of oculars. A number of the St. Pierre speci- 

 mens (22) are of a light cream color, both tests and spines, giving them a very peculiar appear- 

 ance. Specimens of a similar color occur also in material from Puget Sound, Washington, 

 but I have not seen such from any other localities. 



As regards structural characters, the series described from Dumpling Islands, North Haven, 

 Maine, would fall in place at this point, as indicated in the table (p. 143). The Dumpling 

 Islands and the Calderwood Island next considered are both situated in the Fox Island 

 Thoroughfare, at the mouth of Penobscot Bay, into which empties the lai-ge river of the same 

 name. At Calderwood Island, when visited at extremely low course of tides, the Echini are 

 vastly abundant, so numerous that in one morning before breakfast, with the help of an assis- 



