jQg ACTINARIA 



and in other places about Martha's Vineyard (Hargitt) var. albida. Long Island Sound, shores of Nan- 

 tucket, Martha's Vineyard, Cape Cod. — The specimens examined by myself are from Woods Hole (Mc. 

 Murrich) and from Newport (U. S. F. C.) 



Exterior aspect: The proximal part is smooth, and according to the state of contraction, rounded 

 physa-shaped or more flat. Whether it is perforated or not, I cannot with certainty decide as the physa was 

 rather contracted. In sections through a part of the physa I have not found any apertures. The column is 

 cylindrical, elongated and provided with 20 distinct longitudinal furrows, corresponding to the insertions 

 of the mesenteries. The distal part of the column has 20 longitudinal rows of ampuUaceous papillae, each 

 row placed exactly between two insertions of the mesenteries. The rows are not all of the same length. On 

 the parts of the column, adjacent to the 4 lateral endocoels of the first order and the ventral directive endo- 

 coel they are longer than the rows, issuing from the dorsal directive compartment, the endocoels of the second 

 order and the 2 exocoels being next to the dorsal directive endocoel. The remaining exocoel-rows are the 

 shorter and composed of the lesser number of papillae. This arrangement is not always distinct, at any rate 

 the rows belonging to the exocoel-parts of the column seem to be shorter than the other rows. The papillae 

 are larger in the distal part than in the more proximal part; in other words, the papillae originate at the 

 distal part, continuing towards the proximal part. 



The tentacles are 20, short, cylindrical, in the apex hemispherical, in certain states of contraction 

 the distal end is knob-shaped. The 10 inner tentacles are a little shorter than the outer ones, and jaroceed 

 from the endocoels (compare Carlgren, 1904, p. 542). The oral disc is of comparatively small diameter. 

 The entrance to the siphonoglyphe is very distinct, though by far not so deep as in Peachia; its aboral pro- 

 longation is rather long. The actinopharynx is short with numerous longitudinal folds and furrows. 



Anatomical description: Mc. Murrich (1892) has described some anatomical details of this 

 species, but an anatomical examination of all organs has not yet been undertaken. 



The three layers of the column are all of about the same thickness and of ordinary height. The ecto- 

 derm contains numerous typical nematocysts, 17 — 22x2 — 2,5 ji in size, and numerous mucus- and albumen- 

 cells. In the ampuUaceous papillae, which are only evaginations from the body-waU, the ectoderm is a little 

 differentiated from the other parts of the column (textfig. 136, longitudinal section through a piece of the 

 column with a papilla). The mucus-cells namely decrease in number towards the apex of the papillae, while 

 the nematocysts increase a little. 



The main-part of the ectoderm in the apex of the papillae consists of supporting cells. The some- 

 what more numerous nematocysts in the apex indicate tliat we have to do with weak batteries of nemato- 

 cysts. The mesogloea of the column is of a fibrillary structure and contains numerous cell-nuclei. The cavity 

 of the papillae is rather large and in connection with the coelenteron through a narrower canal. In the papil- 

 lae and in the communicating canal the circular muscles are very weak and form no folds, in the other parts 

 of the column the circular muscles have high folds, which are, however, but slightly ramificated. No differ- 

 entiated sphincter present. 



The acrospheres in the apex of the tentacles (fig. 137 uppermost part) differ considerably in struc- 

 ture from the other part of the tentacles, the stalk or peduncle, in as much as the ectoderm is of quite another 



