78 



HYDROIDA II 



Fig. XXXIX. Aglaophenopsis cor mi to. 

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

 dium of the primary tube, showinj' 

 both sarcothecae of the upper pair. — 

 i. Front view of the internode, showing 



opening, and a median proximal sarcotheca, the opening margin of which hardly reache.s up to the 

 middle of the hydrotheca; the sarcotheciE have a dentate margin, and project far forward; the\- are 

 adcanlinally split. The Iiydrotheca 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/. that of the h^-drotheca; 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 gonothecse are set on the stem, or more often on short, 

 once dichotomically divided branchlets proceeding from the basal 

 internodium of the hvdrocladiimi beside its proximal sarcotheca ; the 



the abortive hydrotheca at the base 



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



sarcotheca. (X 40'. , , , , i i .^1 .^1 ^i ^^l 



rarelv the one may ha\e two hydrothecce, 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 upjDer lip, formed b\- the abcladial wall, which is 

 domed forward roofwise over tlie opening. 

 Material : 



"Ingolf St. 15, 66°i8' N., 25°59' W., depth 330 fathoms ^0,75= 



- - 25, • 63-30' N., 54°2.s' W., - 582 - 3,3° 



- - 98, 65°38' N., 26°27' W., - 138 - 5,9° 

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



65°3o' N., 55°36' W., - 289 - 



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

 as to the cauline sarcothec-e, which he describes as follows: ''canline nematophores very large, one 

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

 like oppo.sitc the base of each hydrocladium". As regards the last .sarcotheca (fig. XXXIX c?) 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 colon>- from the front (fig. XXXIX /') 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 b\- the growth of the apophyse and ludro- 

 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 ma)- be formed of internodia with h\drotheca;, but without 



