REPORT ON THE HYDROIDA. 81 



Polyplumaria puniila, n. sp. (PL IV. figs. 7, 8). 



Trophosome. — Colony attaining a height of one or possibly two inches ; stem strongly 

 fascicled and giving oflf opposite pinnae, which do not carry hydrothecse, and are also 

 fascicled ; hydrocladia alternate, scarcely exceeding one-twentieth of an inch in length, 

 borne on the main stem and primary pinnae, each giving ofi" its accessory ramidus from a 

 point close to the base of the proximal hydrotheca ; hydrothecal internodes continuous. 

 Hydrothecse cylindrical, rather distant, adnate only by their base to the rachis, and with 

 the internodes which support them carrying besides the lateral nematophores a single 

 mesial nematophore at the proximal, and another at the distal side of the hydrotheca. 



Gonosome. — Gonangia pyriform, with obliquely truncated summit. 



The specimens were fragmentary, and did not afford sufficient evidence of the size 

 attained by the perfect colony ; but it is probable that it reaches a height of between one 

 and two inches. It is thus a very much smaller, and altogether more delicate species than 

 the Diplopteron insigne of the " Porcupine," which attains a height of about six inches. 



The accessory ramuli carry one, two, or three (possibly in some cases more) hydrothecse, 

 and have a rather long proximal internode, which is always destitute of hydrotheca. 



I was unable to find in the present species the second pair of minute lateral nemato- 

 phores which in Polyplumaria {Diplopteron) insignis is developed at the distal side of 

 the hydrotheca. Polyplumaria p)umila is further distinguished from Polyplumaria 

 insignis by the more cylindrical form of the hydrothecse, which do not present the slightly 

 everted margin which gives a somewhat campanulate form to the hydrothecse of 

 Polyplumaria insignis. All the known species are doubly pinnate. 



The gonangium is borne on a short cylindrical peduncle, and has a truncated summit 

 and a short transverse segment at its very much contracted base. 



All the species as yet discovered are inhabitants of the deeper sea zones. 



Dredged at Station 75, July 2, 1873; lat. 38° 37' N., long. 28° 30' W.; depth, 450 

 fathoms ; bottom, sand. 



Heterophil, nov. gen. 



Name, from €Tepo<;, dissimilar, and ottXov, a weapon, in allusion to the presence of two different 

 kinds of nematophores. 



Generic Character. Trophosome.- — Hydrocladia pinnate ; hydrothecal internode with 

 the lateral nematophores moveable, and with a mesial fixed sj)ine-like nematophore below 

 the hydrotheca. 



Gonosome not known. 



The genus Heteroplon combines the characters of the Eleutheroplean with those of 

 the Statoplean Plumularidse. The hydrothecse are flanked each by a pair of moveable 

 nematophores of precisely the same kind as in the typical Eleutheroplea, while the mesial 



