260 OSTEOLOGY OF TUBINAREK AND STEGANOPODES. 



the distal phalanx of index in the specimens, although the latter under 

 the microscope seems to have a facet there for that purpose. 



The expanded phalanx above this one is not perforated (Fig. 1), as it 

 so often is in the Laridce. The limbs of this skeleton are non-pneumatic. 

 In the pelvic extremity thefemur is comparatively short, its average 

 length being 1.5 0m , the tibio-tarsus measuring 3.8 cm , and the tarso-meta- 

 tarsus 2.5 cm . The femoral shaft is cylindrical and slightly arched for- 

 ward. Its trochanterian ridge is suppressed, being on a level with the 

 summit of the bone, while its head is quite sessile and excavated for 

 the round ligament. Distally its condyles are proportionately devel- 

 oped, the outer one being rather the lower of the two. 



Tibio-tarsus also has quite a straight and smooth shaft, presenting all 

 the characters as commonly seen in the majority of the class. Its own 

 special character, however, which its owner seems to hold in common 

 with the family, consists in a marked prominence of the procnemial 

 ridge over the nearly aborted ectocnemial ridge. Neither of these ex- 

 tend for any distance down the shaft, but are, on the contrary, directed 

 equally upward and forward in rather a striking manner. 



I have failed to discover the presence of a patella in this Petrel, but 

 from the fact that this sesamoid occurs among the Fid mars— birds with 

 a tibia very much like our present subject — I think we are justified in 

 believing that perhaps a very minute one is to be found in the tendon. 



This latter has been scraped away in every instance by the prepara- 

 tor, whereas the tendons at the elbow were allowed to remain. 



The fibula is extremely short and delicately constructed, extending 

 but a very short distance below its ridge on the side of the other leg- 

 bone. 



Hypotarsus of the next segment of this extremity seems to have 

 but a single median groove at its posterior aspect for the guidance of 

 tendons. This is continued for the entire length of the shaft behind, 

 becoming more faintly marked as we descend the bone, while anteri- 

 orly this longitudinal groove is strongly marked. 



The first metatarsal is a diminutive bone, attached to the side of the 

 main shaft at its usual site by ligament. It has articulating with it 

 the ungual joint, the basal one never appearing in these birds. Of the 

 distal trochlea' the inuer one is the most elevated and at the same time 

 most posterior. 



The podal joints of the anterior toes are extremely long and delicate, 

 but otherwise arranged upon the plan most common to the avian foot. 



BRIEF SUMMARY (>r THE OSTEOLOGICAL CHARACTERS OF OCEANO- 



DROMA FURCATA. 



(1) Superior osseous mandible powerfully hooked; culmen convex; 

 nasal holorhinal; lacrymal with long, anterior process, which extends 

 forward to tin- nasal; niaxillo-jngal bar bent at an angle upward to 

 meet descending process of lacrymal. 



