78 



HYDROIDA II 



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

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

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

 pointed at the lower end. The hydrotheca has abcaulinally 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 abeauliue 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 sarcotheea on its lower end. The hydrotheca 



Fig. XXXIX. Aglaophenofsis cortuta. lacks imler ribs 0r Se P ta - 



"Ingolf St. 25. — a. Cauline intemo- T ne gonothecas are set on the stem, or more often on short, 



dium of the primary tube, showing 



both sarcotheea; of the upper pair. — once dichotomically divided branchlets proceeding from the basal 



i. Front view of the internode, showing internodium of the hydrocladium beside its proximal sarcotheea ; the 



the abortive hydrotheca at the base 



of the apophyse above the proximal small branches bear as a rule a hydrotheca on each branchlet; more 



sarcotheea. (X 40). , , , , ., . , ,, m, 



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



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



opening on 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, 66°i8' N., 25°59' W., depth 330 fathoms 



- 25, 6 3 ° 3 o' N, 54 °25' W, - 582 



- 98, 6 5 ° 3 8' N, 26 2 7 ' W, - 138 

 Greenland: Davis Strait, — 100 — (without further details) 



65>' N, 55036' W, - 289 



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

 as to the cauline sarcothecae, which he describes as follows: "cauline nematophores 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 sarcotheea (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 sarcotheea is very broad, and 

 does not project quite as much. The sarcotheea 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 sarcothecae, 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 



o,75 

 3,3° 

 5,9° 



