286 NATURAL HISTORY OF AQUATIC ANIMALS. 



observations were made the 23d, I do not think it can be asserted the eye is closed entirely in 

 spring; and as the same appearance is found in September, we must admit it to be a permanent 

 structure. An analogous membrane is found in the Clupeidce and doubtless other fish. On asking 

 Thomas Loyd, our roughest and oldest fisherman: "I don't know anything about the scales of the 

 eyes, but I do know that, curse them, they see too sharp for us, steering clear ot our spring nets," 

 and doubtless old Tom was right. 



On dissecting a Mackerel, May 23, 1 found the heart first presenting the tricornered ventricle 

 with its white aorta and deep-red auricle resting upon the fringe of cceca that covered the intes- 

 tines, sweeping down to the vent. The liver and stomach were both covered by the coeca. The 

 latter was about three inches long, its upper lobe thick and round, but ending in a narrow tail or 

 point. The cardiac end of the stomach was prolonged two and a half inches, ending in a point. 

 Tlie cfflca were attached to the gut about an inch below the pylorus. There was but little differ- 

 ence in appearance and size between stomach and gut. This we may roughly sum up: Stomach 

 and gut very simple; coaca usually large and complicated; liver small all noteworthy facts in the 

 study of comparative life. The fish being a male one, lobe on either side of ivory-white; milt 

 reached from gills to vent, slightly adhering to the sides by thin membrane, and covered by a 

 similar one. They were divided in lobes by shallow lines, the upper lobes slightly fimbriated. 

 On removing both entrails and milt a dark purple space about an inch wide extended from gills to 

 vent beneath the back bone. This, when opened, seemed tilled with coagulated blood. It had in 

 some respects the appearance of the air-bladder in the Salmonidte, though wanting in the direct 

 communication they have with the oesophagus. But this communication is also wanting in the 

 Oadida, where, especially in the hake, the air-bladder assumes its highest form of organization. 

 I have often found coagulation and reticulated plexi in air-bladders of other fish. 



It has been asserted the European Mackerel have no air-bladders, and a new genus proposed, 

 but with more probability they have the same organization as our own, and the difference lies in 

 the opinion whether or not it is an air-bladder. 



The Mackerel appear on the Atlantic coast of Nova Scotia, and almost simultaneously on the 

 Bay of Fundy, about the 15th of May. Nearly all spawners, male and female, perform a somewhat 

 easterly and northerly route, disappear from the surface in a few weeks and reappear again in 

 September without spawn and fat, remain in numbers during November, and very sparingly during 

 December, coming from the eastward, and then disappear. It may be asserted, generalizing from 

 observation extending over a series of eight or ten years, that they are kregular in their move- 

 ments as regards localities, though probably not as regards ocean surfaces. 



The very great difficulty of accounting how these enormous masses of surface feeders find 

 food after disappearing from the surface has caused many ingenious theories as to the question in 

 what state and where they pass that time. These are all pleasant reading, but valuable more or 

 less as regards the ingenuity and scientific standing of the writers. In this paper and the one I 

 inclose (1865) I have stated what I think are facts, and which must be accepted in the future 

 history of American Mackerel, which I hope soon to see written by that commission which has 

 already done so much in Atlantic waters. 



BERNARD GILPIN. 



The appearance of the mackerel schools at the approach of summer in ordinary years has been 

 noticed somewhere in the neighborhood of the following dates: At sea, off Cape Hatteras, March 

 20 to April 25; off Norfolk, Virginia, March 2 to April 30; off the Capes of Delaware, April 15 to 

 May 1 ; off Barnegat and Sandy Hook, May 5 to May 25, and at the same date along the whole 



