HYDROIDA II 



opening, and a median proximal sarcotheca, the opening margin of which hardly reaches up to the 

 middle of the hydrotheca; the sarcothecse have a dentate margin, and project far forward; they are 

 adcanlinally split. The hydrotheca is laterally compressed; seen from the side, it is egg-shaped and 

 pointed at the lower end. The hydrotheca has abcauliiially a median keel, running out into a large, 

 hollow, generally sharply horn-shaped tooth, the free projecting part of which may reach a length of 



up to 2 / 3 that of the hydrotheca; the cavity forms a continuation of 

 the lumen of the hydrotheca. The hydrotheca margin has at the 

 base of the mentioned projection a median abcauline tooth, and 

 on either side four teeth, which become broader and less pro- 

 nounced nearer the hydrocladium. The internodium has four to six 

 inner ribs at the hydrotheca wall; an inner rib also bounds the 

 lumen of the proximal sarcotheca on its lower end. The hydrotheca 

 lacks inner ribs or septa. 



The gonothecae are set on the stem, or more often on short, 

 once dichotomically divided branchlets proceeding from the basal 

 internodium of the hydrocladium beside its proximal sarcotheca; the 

 small branches bear as a rule a hydrotheca on each branchlet ; more 

 rarely the one may have two hydrothecae, the other one. The gono- 



f 



Fig. XXXIX. Aglaophenopsis cornuta. 

 "Ingolf" St. 25. a. Cauline interno- 

 dium of the primary tube, showing 

 both sarcothecse of the upper pair. 

 6. Front view of the internode, showing 

 the abortive hydrotheca at the base 

 of the apophyse above the proximal 

 sarcotheca. (X 40). 



theca is broad oval to pear-shaped; seen from the side it is somewhat more slender, with subterminal 

 opening 011 the adcladial side and with a short upper lip, formed by the abcladial wall, which is 

 domed forward roofwise over the opening. 

 Material : 



"Ingolf St. 15, 66i8' N., 2559' W., depth 330 fathoms -^0,75 



25, 63 3 o' N, 54-25' W., 582 3,3 



- 98, 6 5 3 8' N, 262 7 ' W, 138 5,9 



Greenland: Davis Strait, 100 (without further details) 



65V N, 55V W, - 289 



In Nutting's description of Aglaophenopsis cornuta (1900 p. 120) there is a misunderstanding 

 as to the cauline sarcothecae, which he describes as follows: "cauline uematophores very large, one 

 just at the base of each hydrocladium, another immediately below this, and a third, long and spur- 

 like opposite the base of each hydrocladium". As regards the last sarcotheca (fig. XXXIX a) this is 

 as a matter of fact one of a pair situate nearer the upper side of the base of the apophyse; both of 

 them project far out from the stem, but on viewing the colony from the front (fig. XXXIX b] the one 

 is hidden by the basal part of the hydrocladium. The lower, proximal sarcotheca is very broad, and 

 does not project quite as much. The sarcotheca which Nutting mentions as just at the base of the 

 hydrocladium, i. e. practically on the apophyse itself, must on the other hand be regarded as an abort- 

 ive hydrotheca which has been checked in its development by the growth of the apophyse and hydro- 

 cladium; it bears no resemblance to the remaining sarcotheca;, and does not seem to be provided with 

 any sarcostyle or nematophore. A point of great importance in this explanation is also the fact that 

 the basal portion of large pinnate parts may be formed of internodia with hydrothecae, but without 



