THE SYNAPTAS OP THE NEW ENGLAND COAST. 
23 
The name and synonymy of the common white synapta of the New England coast 
are therefore: 
Synapta inhaerens, (O. F. Miill.), Zool. Dan. 1779-1784. 
Synapta tenuis, Ayres, Proc. Bos. Soc. Nat. Hist., vol. IV, p. 2. 
girardii, Pourtales, Proc. Am. Ass. Ad. Sci., 1851, p. 14. 
ayresii, Selenka, Zeit. f. wiss. Zool., 1867, vol. xiv, p. 362. 
gracilis, Selenka, Zeit. f. wiss. Zool., 1867, vol. xiv, p. 363. 
Leptosgnapta tenuis, Verrill, Trans. Conn. Acad., vol. i, p. 325. 
girardii, Terrill, Rep. on Inv. Ani. of Vineyard Sound, p. 422. 
The status of Verrill’s Leptosynapta roseola is quite different, and I believe that it 
must be accepted as a valid species. In living specimens there is never the slightest 
difficulty in distinguishing between roseola and inhcerens. I have never seen but one 
specimen in which the color alone was not sufficient to distinguish them, and in that 
specimen even a very superficial examination showed that it was roseola. Alcoliol 
makes the color differences even more marked, so that in preserved material the two 
species are very' easily separated. But there are three points in the microscopic 
anatomy of roseola which serve to distinguish it readily from inhcerens , and on these 
three points its claim to good standing as a species must rest: 
(1) The most important point is found in the radial plates of the calcareous ring. 
In inhcerens these plates are about three-fourths as high as broad, and each is perfo- 
rated through the center for the passage of the radial nerve. In roseola , on the other 
hand, the radial plates are oidy about half as high as they are wide, and they are not 
perforated, the radial nerve passing over the top of each in a shallow notch. At first I 
thought this was simply a stage of development in the formation of the plate, but I was 
finally convinced that such could not be the case. No specimen of inhcerens, however 
small and immature, had a radial plate which was not distinctly perforated through the 
center, and no specimen of roseola , however large, showed any condition beyond the 
notch. The differences in the calcareous ring are shown in figs. 1 and 2, plate 11. 
(2) The calcareous spicules of the body wall present the second distinguishing 
characteristic: of roseola. In form, proportions, and distribution of anchors and plates 
I could find no constant differences between the two species; and Verrill errs in saying 
that in roseola “the perforated plates are smaller and the anchors relatively much 
longer, with a very slender elongated shaft.” Careful measurements, with the aid of a 
camera lucida, of a large number of anchors and plates taken at random in specimens 
of roseola and inhcerens from Naples and from Woods Hole, gave the following results: 
Species and locality. 
Length 
of 
anchor. 
Breadth 
of shaft. 
Ratio of 
breadth 
to 
length. 
Length 
of 
arms. 
Ratio to 
length 
of 
anchor. 
Breadth 
of 
arras. 
Ratio to 
length 
of 
anchor. 
Length 
of 
plate. 
Ratio to 
length 
of 
anchor. 
Breadth 
of 
plate. 
Ratio to 
length 
of 
anchor. 
Inhaerens, Naples 
177 m 
17+ m 
. 10 
44 ix 
.25 
83 m 
.47 
131 f x 
.77 
ioom 
.56 
Inhaerens, Mass 
161 
17+ 
108 
49 
.30 
92 
.56 
135 
.82 
93 
.57 
Roseola, Mass 
142 
16 
11 
38 
.27 
76 
.53 
115 
.81 
72 
.57 
ix Abbreviation for micron. 
In a still larger series: 
Species and locality. 
Average 
length of 
anchor. 
Average 
length of 
plate. 
Ratio of 
plate to 
anchor. 
Inhserens, Naples 
179m 
133 m 
.74 
Inhasren^, Massachusetts 
177 
139 
.78 
Roseola, Massachusetts 
164 
131 
.79 
