. Bulletin - United States National Museum. Science. 136 UNITED STATES NATIONAL MUSEUM BULLETIN 247 small foramina, and one in front of it. Most of the right incisure was destroyed when the posterior end of this maxillary broke off; this incisure terminates 52 mm. inside of die outer edge of this bone. Four smaller foramina are located anterior to the incisure. No other fossil mysticete having a similarly modified maxillary seems to have been recorded in the literature. A lithographic plate (True, 1907, pi. 6) prepared in 1850 under the supervision of Louis Agassiz for the type skull of Agorop
. Bulletin - United States National Museum. Science. 136 UNITED STATES NATIONAL MUSEUM BULLETIN 247 small foramina, and one in front of it. Most of the right incisure was destroyed when the posterior end of this maxillary broke off; this incisure terminates 52 mm. inside of die outer edge of this bone. Four smaller foramina are located anterior to the incisure. No other fossil mysticete having a similarly modified maxillary seems to have been recorded in the literature. A lithographic plate (True, 1907, pi. 6) prepared in 1850 under the supervision of Louis Agassiz for the type skull of Agorophius pygmaeus, however, shows a relatively large circular foramen in each maxillary in a position com- parable to tliis maxillary incisure. Dissection of a fetal female finback {Balaenoptera physalus) by Walmsley (1938, p. 142-143, fig. 14) has shown that the main maxillary artery after passing forward along the pterygoid divides into a leash of small branches that pass ventraUy into the maxillary bone to supply the baleen plates. Branches of a superficial temporal branch of this maxillary artery pass forward to the top of the snout where they divide further into a "leash of exceedingly fine ; This portion of the rostrum is drained by the maxillary vein. Skulls of Recent as well as fossil mysticetes, whose rostra are sufficiently complete to permit detailed com- parisons, have the maxillaries pierced dorsally by one or more relatively small foramina for the passage of vascular vessels and nerves, but at more anterior and inward positions. In the absence of even a sketchy geological record of the sequence of prior adaptive alterations, the infraorbital foramen of the carnivore skull may also furnish a clew as to the functional purpose of tliis elongate maxillary incisure. Some of the carnivores, at least, have infraorbital nerves, which are terminal branches of the maxillary nerve (Trige- minus II) that accompany the infraorbital branches of the internal maxillar
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