0PISTH0BR4NCHIATA FROM THE ABROLHOS ISLANDS. 535 
RMnophores. The two rhinophores lie fairly close together, dorsall}', just 
behind the oral tentacles and nearer to them than to the slit between the 
pleiiropodia. Their extremities are grooved postero-laterally, but they are 
not so dilated as in some members of the genus. 
Gill or Ctenidium. The gill is composed of a single lamelhited plume with 
the lamellae lying longitudinally, and it runs more or less transversely across 
the animal. 
Shell. The shell was very small, calcareous, and apparently trapezoidal, but 
was too crushed to allow of accurate description. 
Labial Armature. The labial armature, if present at all, is only very feebly 
developed. 
Radula. The radula is not large, but the teeth are well developed. The 
total number of rows is 31. The first row consisted of 2 (i.e., 1.1.0), the 
fifth row of 27 (i. e., 13. 1. 13), and the twenty-fourth of 57 (z. e., 28. 1. 28). 
The rachidial tooth has a broad trapezoidal basal plate, which is incurved on 
both its anterior and posterior edges. The blade consists of a median spine 
bearing two tiny laterals, and four smaller but almost equally developed spines 
lie on each side of this. The basal plate of the inner pleurals is rhomboidal 
witii incurving long sides, and the blade consists of four large spines of which 
that nearest the rachis is usually the largest. Further out the spines become 
extremely large, and the one nearest the rachis much the largest, so that the 
others are borne on its outer side. The outermost pleurals still have a large 
inner spine, but the next one to it is almost as well developed, and so they 
appear bifid. 
In general, the teeth are somewhat similar in type to those of Tethijs, but 
they differ sufficiently to be recognised as of a difi'erent genus. 
The genital aperture lies under the mantle-edge well in front of the .gill. 
The seminal groove passes forwards to the penis, which is situated just below 
the right cephalic tentacle. 
The anus opens on the right side of the middle line behind the gill. 
Notes. The two specimens in the collection were both collected on Pelsurt 
Island. 
They do not appear to be referable to any previously described forms, and 
so have been recorded here as a new species with the name Dolahrifera 
■pelsartensis from the island on which they were taken. 
(3) TECTIBRANCHIATA NOTASPIDEA Fischer, 1884. 
The mantle is well developed and covers the whole dorsal surface. It 
contains a somewhat small concave lamellar shell within a large pallial cavity. 
The shell may be absent or may itself be hidden by an external shell. The 
oral veil is marked and carries two dorsal tentacles (rhinophores). The gills 
are pinnate and situated laterally on the right side of the body. 
