166 PROCEEDINGS OP THE ACADEMY OF 



Boreocottus Gill. 



Body subcjlindrical, rapidly declining to the caudal fin. Skin mostly naked, 

 or with small and distant tubercles above the lateral line. Lateral line open- 

 ing on the sides through small distant pores. Head large, depressed and sub- 

 rhomboidal ; nasal spines small ; preopercle with two simple spines near the 

 angle and two tubercles below ; opercle with a longitudinal rib terminating in 

 a spine, and with a rounded membranous margin ; subopercle with a spine 

 directed downwards. Postorbital longitudinal crests little developed. Mouth 

 moderate. Teeth villiform, present on each jaw and on the front of the vomer. 

 Branchiostegal membrane continuous under the throat, but attached along the 

 middle of its length almost to its margin, and thus nearly restricting the bran- 

 chial apertures to their respective sides. Branchiostegal rays six. Dorsals 

 separate ; the first low, highest at the middle. Ventrals small, moderately ap- 

 proximated and behind the pectorals ; each with a spine and three soft rays. 



B. axillaris Gill. The color is purplish-blue, with whitish spots on the 

 trunk, and with a darker band-like spot below the anterior portion of the second 

 dorsal. The abdomen is whitish-yellow ; the tail above the anal dotted, and 

 higher up with dark spots confluent with the deep color of the sides. The first 

 dorsal has two vertical dark bands ; the second, three oblique ones. The caudal 

 is blackish at the base and vertically banded with an undulating dark band at 

 its posterior third. The anal has a very irregular row of spots. The pectorals 

 are dark near the base, and have two oblique irregular bands on the posterior 

 half, and a dark spot at their inferior axillae. 



D ix. 15. 



One specimen caught with the Porocottus quadrifilis Gill, was obtained 

 Behring's Straits. 



Boreocottus is especially distinguished by its subrhomboidal head, sim- 

 ple preopercular spines, vomerine teeth and six branchial rays. 



Porocottus Gill. 



Body anteriorly subcylindrical, rapidly declining to the caudal. Skin naked- 

 Lateral line opening by pores in raised papillae, under a cutaneous keel. Head 

 large and depressed, subrhomboidal. Nasal spines small. Preopercle with a 

 single hooked spine. Opercle without a longitudinal rib or spine. Large pores 

 under the lower jaw and on various parts of the head. Mouth moderate. Teeth 

 on the jaws and front of the vomer. Branchiostegal membrane continuous un- 

 der the throat, but attached along the middle to the throat, almost as far as the 

 margin. Branchiostegal rays five. Dorsals separate ; the first low; the second 

 oblong and opposite the anal. Ventrals small, behind the pectorals, each with 

 a spine and three soft rays. 



The Porocotti have a strong resemblance to the Boreocotti, but are 

 distinguished by the naked skin, hooked preopercular spine, the absence of a 

 longitudinal rib on the opercle, numerous pores, and the presence of only five 

 branchiostegal rays. 



P. quadrifilis Gill. The color is purple, irregularly spotted with black. 

 There is a dark spot under the eye, and another on the maxillary. The dorsals, 

 caudal and pectorals are irregularly variegated with black. On the pectorals 

 there is a dark spot at the upper axilla, and another larger one towards the 

 middle of the base. There is a slender superciliary filament and one on each 

 side of the nape. It is to the presence of these that the specific name is 

 designed to draw attention. 



D viii. 13. 



Specimens were obtained in Behring's Straits at the same time as Boreo- 

 cottus axillaris Gill. 



[June; 



