BIGELOW: THE "GRAMPUS" IN THE GULF STREAM. 205 



Temperatures. 



The few temperatures observed during the voyage are of interest as ad- 

 ditions to the records of the temperature conditions of the Gulf Stream. 

 The highest surface temperature was 76°, the lowest within the sweep of 

 the Stream, 72°. The most important feature of the observations is their 

 renewed demonstration of the shallowness of the surface layer of warm 

 water in this region. Thus at Station 5, where the highest surface tem- 

 perature (76°) was observed, at 100 fathoms the temperature was only 

 49.5°, a drop of over 26°. And the highest temperature observed at 

 100 fathoms was only 51.5°. The temperatures are shown in the table, 

 (p. 210). 



Description op a New Medusa. 



Bythotiaridae Maas, 1905. 

 sens. em. Bigelow, 1909. 



This family is of such importance from its morphologic relations on the one 

 hand to the Tiaridae and on the other to the Williidae, that a new species is of 

 unusual interest. More especially is this the case since up to the present time 

 only eight individuals (representing the genera Bythotiara Guenther, Heterotiara 

 Maas, and Sibogila Maas) have been described which can certainly be referred to 

 it, though two other genera, Dichotomia Brooks, and Netocertoides Mayer, may 

 find their place here. The specimens collected by the " Grampus " are typical 

 members of Sibogita. 



Sibogita Maas, 1905. 



sens. em. Bigelow, 1909. 



Bythotiaridae with four primary radial canals, and in addition, numerous centrip- 

 etal canals which may secondarily come to join either the cruciform base of the 

 manubrium or the radial canals, or may remain blind. Gonads transversely 

 folded. 



Two species have previously been referred to this genus, S. geometrica Maas 

 (the type), and S. simulant Bigelow, the first from the Malaysian region, the 

 second' from the west coast of America. From my studies on S. simulans x I 

 maintained that the branching of the canals described by Maas in S. geometrica 

 was a secondary condition, resulting from a uniou of blind centripetal canals with 

 the cruciform base of the manubrium or with canals of an earlier generation. In- 

 asmuch as a secondary junction of canals with manubrium probably occurs in S. 

 geometrica, as well as in S. simulans, I believed that it was characteristic of the 

 genus. In the present series, however, the centripetal canals all end blindly, 

 although the specimens are apparently mature. This difference should not be 



i Mem. Mus. Comp. Zool., 37, p. 21€, 1909. 



