62 AMERICAN HYDROI1JS. 



PLUMULARIA ALTERNATA, new species. 

 (Plate IV, figs. 1,2.) 



Trophosome. Colony attaining a height of about one-third inch in the single specimen exam- 

 ined, unbrauched ; stem iiot fascicled, divided into regular interuodes every alternate one of which 

 bears a liydrotheca on the front of its distal end, and also a lateral process bearing a hydrocladium ; 

 a slight bend in the stem behind each of the caulinc hydrothec;i' imparts a wavy or geniculate aspect 

 to the colony; hydrocladia distant, divided into alternating hydrothecate and intermediate inter- 

 nodes of nearly equal length, each intermediate internode having a distal oblique and proximal 

 transverse node. Hydrotliec;i' large, rather closely approximated, conical in front view and deeply 

 cup-shaped in lateral view, free for about their distal one-third, margin slightly everted; lateral 

 nematophores borne on strong processes of the ink-modes, and reaching to the margin of the liydro- 

 theca; a mesial nematophore below the base of each hydrotheca and one on each intermediate 

 internode; the arrangement of the cauliue hydrotheca' is as described above. 



Gonosomc. Not known. 



Distribution. Barracuda llocks. Collected by Alexander Agassiz, during the cruise of tbe 

 Wild Dud; in the West Indies, in 1893. 



This very distinct species is sharply characterized by alternate hydrocladia in connection with 

 cauline hydrotheca. 1 , and by having a single mesial nematophore to each iuternode both of stem 

 and hydrocladia. 



Type. In the Museum of Comparative Zoology, Cambridge, Massachusetts. 



PLUMULARIA PLUMULARIOIDES (Clark). 



(Plate IV, fig. 3.) 

 Halecium plumularioides CLARK, Proc. Acad. Nat. Sci. Pliila., 1876, Pt. 3, p. 217, pi. x, figs. 16, 17. 



Trophosome. Hydrocaulus erect, simple, straight, divided by transverse joints into internodes 

 of considerable length, regularly branched, and with a few annulations at the base; branches 

 arranged alternately on opposite sides of the stem, one to each internode, having their origin in a 

 small shoulder like process just below each joint, divided usually into regular internodes, though, 

 in some cases, short intermediate iutei nodes occur between the longer ones. Hydrothecie arranged 

 uniserially, usually one to each internode, partly adherent to the stem, or entirely free, shallow, 

 tapering slightly to the base, with an entire rim. 



Gonosomc. Gonangia unknown. 



Distribution. Cape Etoliu, Nuuivak Island, 8 to 10 fathoms. Height of largest specimen, 

 20 millimeters. 1 



Dr. Clark refers this species to Halccinm on account of the absence of nematophores. This, 

 as we now know, is a feature that may be only accidental or temporary, and hence is of little system- 

 atic importance. 



Clark's figure shows that this species is without intermediate internodes, and that the hydro- 

 theca' are near the distal ends of the int> modes with their posterior margins on a level with the 

 nodal joints. 



PLUMULARIA INERMIS, new species. 

 (Plate V, figs. 1, 2, 2o.) 



Trophosome. Colony unbranched, attaining a height of about one-half inch; stem not fasci- 

 cled, strongly sinuous, almost geniculate, divided into interuodes each of which bears a hydrocla- 

 dium on a projection from its distal end; hydrocladia rather distant and slender, projecting at 

 almost a right angle from the stem, basal internode bearing a hydrotheca near its distal end, the 

 remaining internodes long, slender, each with a hydrotheca near its distal end; an occasional 

 intermediate internode appears. Ilydrothecic distant, small, subcouical; nematophores minute, 

 supracalycine pair usually absent; a single nematophore below the base of each hydrotheca, and 

 sometimes one above each hydrotheca, and one just above the axil of each hydrocladium; 



1 Original description. 



