The only area on the north shore of Cape Cod itself where I have done much collecting is Barnstable harbor. This area is somewhat different from the tidal areas of the south shore, but it is also different from most of the Cape Cod Bay (north shore) coastline. Because it is a long, sheltered, rather shallow bay, the wave action is greatly reduced, and the temperature is warmer than other areas of the north shore. But it is still colder than similar sheltered bays on the south shore. As you would expect in a sheltered cul de sac without much wave action, many of the beaches here are muddy or muddy sand. Quite a few of the south shore species are still present here (Ensis, Petricola, Nucula, Mytilus, Crassostrea, Mercenaria, Gemma, Tellina, Nassarius trivittatus, Nassarius obsoletus, Littorina littorea, Crepidula fornicata, Crepidula plana, Urosalpinx cinerea). But other south shore species are absent, or rare (Anadara, Anomia, Laevicardium, Tagelus, Epitonium, Eupleura, Anachis, Mitrella, Busycon, Nassarius vibex, Haminoea, Polinices duplicatus, Crepidula convexa). And, other species which are not found on the south shore (or which are found only in deeper water) occur intertidally here (Siliqua costata, Macoma balthica, Modiolus modiolus). To really get a taste of cold water New England collecting though, you have to leave Cape Cod and drive a few miles up route 3 from Sagamore, at the east end of the Cape Cod Canal. My favorite location is Manomet Point in the town of Manomet. This is a typical New England cold water, surf-washed, rock and seaweed habitat. Huge boulders are everywhere, covered with shaggy coats of Fucus and Ascophyllum seaweed, with patches of sand and rocky tide pools dispersed among them. The water, even on a hot summer day, numbs your feet in about 10 minutes. Snorkeling requires a wetsuit, to avoid hypothermia. In the tidal pools, Nucella lapillus, Acmaea testudinalis, Littorina littorea, and Littorina obtusata are the most obvious mollusks. Shake a couple of handfuls of rockweed into a bucket and you may get 50 or more L. obtusata, in a variety of colors. This location has the largest Littorina littorea I have seen, up to about 35 mm. I have found Margarites helicinus and Margarites groenlandicus once in a while. Lunatia heros and Lunatia triseriata can sometimes be found in the lower tidal zone. Even Buccinum undatum and Colus stimpsoni occasionally end up stranded in the lower tidal zone, though they prefer deeper water. Large Modiolus modiolus attach to the bases of boulders. Hiatella arctica can be found under rocks in the lower tidal zone, and Mesodesma arctata in sand pockets. Brittle stars, blood starfish, sea cucumbers, green crabs, and green sea urchins are also common. There are also some great species just offshore, which unfortunately are not found intertidally, like Calliostoma bairdi, Aporrhais occidentalis, Neptunea decemcostata, Placopecten magellanicus, and Chlamys islandica. The vertical tidal range here is about 8 feet, and once the tide starts coming in, it comes in pretty fast - not as fast as the Bay of Fundy, but you still have to keep your eyes open. More than once I have lingered a bit too long, and had to wade through a waist-deep channel of frigid water to get back to shore. Hope you enjoy Massachusetts. It's where I lived most of my life, even though I'm in Rhode Island now (just a few yards south). Regards, Paul M.