18 



AMERICAN HYDRO-IDS. 



the terminal aperture from the part facing the .stem; second, an elongation of the latter nemato- 

 phore, with a plain (tig. 00) or crenulatcd (tig. Go') aperture; third, a notable broadening of the 

 distal portion of the nematophore and a tendency toward the formation of two apertures at the 

 upper corners (fig. 70). This latter type is carried to an extreme in Ai/hioj)henopsin hirnuta (fig. 64), 

 in which there appears to be a pair of nematophores, while in reality there is a single one which is 

 forked and has two distal branches, each with a distinct aperture. The largest cauline uemato- 

 phores are found in the portion of the genus Lytocarpus embraced in the genus Nematophorus of 



73 



TYPICAL NEMATOPHURES OF THE STATOPLEA. HlU'h enlarged. 



Fig. 64. Aglaophenopsis hirmta, mesial. Fig. lO.L.furcatus, cauline, showing neinatocysts. 



Fig. 65. A. hirsuta, gonosomal. Fig. 71 Xvditlicca dalli, mesial. 



Fig. 66. A. hireuta, cauline. Fig. 72. A', dalli, aiipracalycine. 



Fig. 67 Lytttcarpits clarkei, aupracalyuine. Fig. 73.Halicin-uiiria litmjicaitda, mesial. 



Fig. 68. L. furcatus, supracal.ycine. Fig. 74. Aglauphmia sji. (after vim Lendenfeld). Much less 



Fig. 69. L. curtus, cauline. a, perforated process. magnified than the other figures- 



Clarke. In some cases these are almost half as high as the hydrothecre. Aglaoplienopsia cornuta 

 Verrill also has remarkably large cauline nematophores which are very beautifully crenulated 

 around the margin. 



In many species of both groups of I'lumularidiu a careful examination at the base of the 

 hydrocladium will reveal a more or less prominent conical, inammillate, or tubular projection with 

 a round aperture at its summit. This is usually regarded as a ucuiatophore. Allinan, the first to 

 call attention to the structures under consideration, in his description of Af/laophenia perpusilla 

 speaks of the process as bearing a nematophore. 1 The best example of this structure is found in 



1 Report on the Hydroida collected during the Exploration of the Gulf Stream by L. F. Do Pourtalcs, Memoirs of 

 the Museum of Comparative Zoology, V, No. 2, 1877, p. 48. 



