65 



From this, it seems most probable, judging from observations liitherto made, that Orca females give birth to 

 their young towards the end of tlie year, late in November and in December. Copulation probably takes place 

 at the same time of year, the gravid period being 12 months, which Grieg also supposes to be the case. 



The young one caught at the end of January, 1891, may without doubt be taken to be between 1 and 1 V2 months old. 



The length of the new-born animal is probably rather more than 2 metres (2.08 — 2.20) and, as an average, ought 

 to be taken as -/o of that of the mother. The facts here stated are, of course, too few to allow of our drawing certain 

 conclusions, and giving fixed measurements, but I have every reason to believe that they do not greatly differ from the actual 

 circumstances, as we have analogies in other species of Odontoceti. 



4. On gravidity in Phocæna communis, Lesson. 



As the curator, James A. Grieg (1. c), on a basis formed by the rich material in the Bergen Museum, has 

 treated very exhaustively the subject of the gravidity of the common porpoise with regard to its duration and the time of 

 copulation, I shall only subjoin a few remarks, adding some new observations, and comparing them with those previously 

 made by Grieg. 



7 millim. long, measured by G. Guldberg. 



17 - „ - „ - 



18 ^ „ — „ — 

 137 - „ - „ 



„ 1893, — — ... 115 — ,, — „ 



19th, 1888, — — - „ 12.0 — „ — „ 



Aug. 

 Sept. 



Oct. 



.31st, 1892') Mr. Bistrup, Greenland, a feetus 

 12th, „ - - - „ 



18th. 1888. Dr. Nansen. - „ 



12th, 1889, Bergen Museum, 

 14th, „ - - 



A. Grieg. 



86 



f according to information supplied 

 I by Dr. Danielssen. 

 measured by J. A. Grieg, 

 according to the curator, Storm, 

 according to J. A. Grieg. 



„ 26th, 1892, — — 



Nov. 3rd, 1893, — — 



In Nov. 1889, Museum in Throndhjem 



Nov. 13th, ,, Bergen Museum, 



26th, 1886, — — 



Dec. 4th, 1888, — — 



,, 9th or 19th 1891, — — 



Jan. 17th, 1890, — — 



28th, 1884, — — 



Feb. 10th, 1893, — — 



,, 28th, 1881, — — 



„ 29th, 1892, — — 

 In March, the length varies from 

 From 15tii to 29th April 



„ 3rd to lOth May ,. 



„ 2nd to 22nd June „ 



From the above scale of measurements, in which I have only taken notice of measurements made by Dr. Danielssen, 

 James Grieg, Storm and myself, it appears that the porpoise, in the northern parts of the Atlantic and in the Arctic 

 Ocean is pregnant for 10 months or possibly longer, as the conception of the 7 millim. long embryo taken on Aug. 

 31st is assigned to the beginning of that month. The fully-developed fretus has probably an average length of 

 800 millim., and the birth probably takes place in the month of June, either before or at Midsummer. 



.James Grieg, in his treatise, has mentioned the most important observations in the literature upon the gravidity 

 of the Phocæna. As a number of the earlier observations and measurements were not made with special reference to the 

 subject in hand, in which it is of importance that not only the length of the fætus, but also the time of the mother animal's 

 capture be given with absolute accuracy, I have only placed in the above table such measurements as I know to be accurate. 

 Were we to take all the instances in literature, there would immediately arise greater variations and uncertainty. The reason 



Dr. Danielssen. 

 J. A. Grieg. 



,, — - Dr. Danielssen. 



according to ,J. A. Grieg. 



') .James A. Grieg, mentions, in his treatise, a fætus taken in Troniliijem's Kjonl in Aug. 1887, which, according to Storm, measured 

 45 centim. (according to my measurement of the specimen preserved in alcoliol, 41 centim.) Tliis dimension differs so considerably from tlie rest, 

 tliat I must disregard it until furtlier facts are forthcomiuL'. 



