64 U.S. NATIONAL MUSEUM BULLETIN 234 



lobes. The posterior ends of the fins extend past the blunt end of the 

 body. 



The funnel is small and compact, free for only a small part at the 

 end. In most of the specimens, the aperture is turned strongly 

 ventrad and even slightly posteriorly. There is a subterminal valve. 

 The dorsal member of the funnel organ is an inverted V -shape with 

 broad arms which end bluntly. There is a small sharp anterior point 

 and the posterior margin is roundly concave. The ventral pads are 

 oval, either rounded or sometimes slightly pointed. The mantle 

 locking apparatus consists of a flattened nose-shaped plug and a 

 deep oval socket, deepest posteriorly. The resulting articulation is 

 rather strong. 



The head is small and compact, its width less than that of the 

 mantle. A noticeable neck region extends beyond the mantle margin 

 in the males, but in the females it is shorter. The eyes are small and 

 deeply set, with a minute anterior pore. There is a small olfactory 

 pit posterior to each eye and beneath the mantle margin. 



The arms are short and stout, with blunt points, and in the order 

 of 2.3.1.4. They are slightly compressed and without keels. There 

 is a low web between III and IV which partly encloses the tentacles. 

 The suckers are biserial, round, and with small apparently smooth 

 apertures. There are about 16 pairs on the lateral arms. In the 

 males, the arm suckers on I, II, III, and IV appear somewhat larger 

 than in the females. 



In the males, both ventral arms are hectocotylized. Both arms 

 are devoid of suckers except at the base where may be found, in the 

 Philippine specimens, one to three small round suckers. Usually the 

 number is the same on each arm, but it may vary from 3-3, 3-2, 3-1, 

 2-2, 2-1, to 1-1, showing a tendency towards greater reduction on 

 the right arm. When there are three on left IV, two are in the ventral 

 row and one is in the dorsal row. In well-preserved specimens, there 

 are a number of transverse rugae, thick and gelatinous, on the oral 

 surface above the suckers and extending towards the tip. The 

 right arm is always much stouter than the left, and somewhat tri- 

 angular. On each side of the arm is a thin transparent or whitish 

 keel which is rolled back aboraUy to form a broad smooth groove 

 from the base to the tip, the latter being inroUed towards the mouth. 

 The left ventral arm is slim, nearly round in cross-section, and about 

 equal in length with the right, but in a few males it is shorter. The 

 tip is flattened into a smaU lamina which lies in an oral-aboral plane. 

 Just below the flattened tip is another small, semicu-cular or quadrate 

 flap, partly curled about the arm. The function of the various parts 

 is not known. 



