OCULAR AND GENITAL PLATKS. 139 



have the typical character of oculars I, V insert. In 0.9%, ocular I only is in-ert. and in 

 2.6 % oculars I, V, IV are insert; one specimen, 0.1 %, has I, V, IV, II in-ert. It i- int. 

 ing to see how regularly this rare progressive variant crops out in almoHt every large series. 

 The aberrant variants are few, eight specimens, or 0.8%. Of tin-,., tw., have \ I\ . ami 

 six I, V, II insert. In the percentage of typical arrangement also of arrested, pn>nr<- 

 and aberrant variants, the Puget Sound specimens are extremely close to those from York. 

 Maine, but are slightly more progressive. In this lot there are ten specimens, 1 <;; , which arc 

 light cream color, similar to the color commonly seen in Echinus aculus or affinis. Thi- peculiar 

 color was also seen in specimens from St. Pierre, Newfoundland, as noted, but from no other 

 locality. It is interesting to see how closely one can correlate not only the typical character 

 but also -the relative frequence of variations in specimens collected at such widely distant 

 localities. 



From Massachusetts Bay, mostly in tide pools at Nahant, a series of 5SX .-pecimen.- \\:i- 

 examined. Of these, 1.4 % have ocular I only insert; 95 % have I, V; and 2.2 ' , have ocular- 

 I, V, IV insert. One specimen (text-fig. 139a, p. 132) has oculars I, V, IV, II insert, the 

 extreme progressive variant of the species. The aberrant variants, 1.5%, are one >pecimcn 

 with oculars I, IV insert; one with V, IV; and seven with I, V, II insert. This is an unusually 

 large proportion of I, V, II for a locality where I, V, IV is at all common. 



Through the kindness of Mr. Dwight Blaney of Boston, and from my own collecting, a 

 series of specimens was obtained from Frenchman's Bay, Maine. They were all from -hallow 

 water, and varied from small to large, though none was very young. Of this serie- 1. (MX) 

 specimens) one, 0.03%, has all oculars exsert, an extreme and very rare arrested variant text- 

 fig. 135, p. 132). It is the only one found in the species except as it occurs in a very early 

 stage as a developing character. In 1.9% ocular I only is insert; in 94'',' ocular- [. V; and 

 in 3.3% oculars I, V, IV are insert. In two specimens, or 0.05% oculars I. V. IV. II are 

 insert. This shows a distinct gain in progressive variants over those previously rnn>idcred. 

 In several of the following series there are no cases of I, V, IV, II insort, but this is so 

 rare a character, that it cannot be expected in small series. In large series it appear-, how- 

 ever, with marked regularity as shown in the table. The aberrant variants of Frenchman's 

 Bay are 47 specimens, or 1 %. They are in detail, one specimen with ocular II only insert, a 

 very rare variant; eight have oculars I, IV insert; four have I, II; five V. II; and twenty- 

 nine have I, V, II insert. 



From Harpswell, Maine, through the kindness of Dr. F. D. Lambert, of Tufts College. 

 I have 300 specimens. They are all large individuals. Of arrested variant-, 

 ocular I only insert, one has V only, 92 % have I, V, and 3.7 % I, V, IV insert. The alx-rrant> 

 are 1 %. Of these, two specimens have oculars V, II insert and one I, V, II insort. 



Through the kindness of Mr. J. Henry Blake, specimens were obtained from Truro, Massa- 



